Electric Valve Body Prototype



old design for 1st/reverse only

line pressure constant to the rear band then control psi to the direct and forward clutch assemblies . maintain direct/reverse clutch bleed to apply via a controlled orifice in the set crew in the center support. forward is un-metered. the valve to do the job was tentatively found and available for 150 bucks. system pressure still dictated by front pump modifications and at this point not impede system opressure to cooler or converter/lube circuits.

1/2 inch steel plate with 1/4″ pipe tapping will replace the valve body with 4 lines to a hydraulic control valve. this would be line in-forward-reverse-and bleed to sump. open center valve. this would work to eliminate shifter but leave 4 hydraulic lines….actually 6 hydraulic lines to rupture causing not only a routing issue but a safety hazzard.

it was built never finished. wasn’t right. new design concept:

i need electric over hydraulic.  base design using 4L60 or 4L80 technology is more desireable. accessable parts and solenoids. i think we can keep the constant flow to the rear band for 1st/reverse hold and use the two prong plug off the older th400 kickdown. one would be used for forward and one for reverse triggering. obviously neutral would be no power but fluid would still flow to the rear band via line pressure. free flow of clutches to sump while line is blocked off completely. this would be better as if i went open center with old design i may lose all system pressure bypassing the regulator feeding everything else to converter-cooler-lubricating. so we need  two triggering solenoids to that both deadhead line psi when not engaged and vent the clutch pack.

basically we are looking at a custom valve body out of aluminum with two spool valves- fed by line pressure and allowed to vent to sump off the clutch pack when dissengaged. each valve would have independent constant pressure from the control line off the regulator. when energized the vent port would close and line pressure sent to that clutch pack. when de-energized a spring would return the valve to vent the clutch fluid as well and block off the line psi to maintain system pressure.

so what we are looking at is two spool valves most likely normally closed to line psi while maintaining vent to the clutches. basic two power wires out the transmission and system is grounded through the case/chassis. when energized it engages a clutch. all shift controlling would be done externally this would cut cost and simplify the routing of wiring to trigger the car.

to prevent multiple clutch lock up we could use an industrial controller which automatically dissengages one power while engaging the other, and leave a toggle switch for neutral next to the two place switch. basically and arming switch. possibly have a solenoid to hit and dissengage park next to the arming switch. either way i think a two place switch is the way to go either forward or reverse no neutral. simplfy the shift and leave neutral or park separate. therefore eliminating false shift

looking at if i am thinking 2 inch thick aluminum with a custom 4-6 inch deep pan. i am thinkin either no filter or a custom filter “sock” of some kind. no paper element.

grove on the line psi side  toward the right of the diagram for supply, then cut the port to the left side supplying fluid to a trigger over the direct-reverse passage and following through to the rear servo. the forward clutch valve/trigger oil/spool is a different story. being at the front i can either run it sideways over the old rooster head manual shift area of replumb it to the rear next to the reverse spool.

here again we leave some kind of solenoid to trigger a park or abandon it all together, which is not an option to me. overall the valve body is only concerned with 1 supply line-1 constant supply while running- and two control ports. if we need a second gear it would be three ports and there is a possibility of using two solenoids both energized to create a 2nd gear shift via spool valving, but it is over complex and unnecessary at this point.

so at this point i have the concept but i need to figure out the valving and the solenoids. we are going with an aluminum plate for the control body for sure. re-examine gm electric tranny stuff i think would be the way to go. if we can find an existing valve to use and simply use one part of both. also could we use i long valve on one solenoid to move it forward after armed and energize solenoid for reverse. forward being the stronger end of the car in failure AND stronger circuit for the most part. even in this design we would need a separate arming solenoid to dissengage the tranny but would be a simple circuit such as a TCC circuit in comparison to the rest. this would leave one valve for machining reducing cost.

if we do two inch thick we can tier the passages, however 1″ with one valve also simplifies cost and machining as well. we have a cost factor. so we do a static passage to the rear servo-to supply one valve. no energized we got forward/reverse energized. a second valve would have to vent and deadhead line psi. either we use two control valves of 1 control valve and one arming valve. it would be left up to a cost issue.

the overall goal is a 1 or 2 wire control valve body on the existing design of th400 1st/reverse only. possibly an upgrade for existing trannys.

it appears that the modern solenoids control the oil flow via an internal pintle on the valve on the solenoid to move the main valve to trigger shift. this adds a layer of complexity. we will be looking at an oil tolerant valve from the old design to go into the pan. these exist in an industrial enviroment. engineering two oil circuits to accomplish one goal is ridiculous. i am thinkin two valves-oil tolerant externally to go in the pan, leave the valve body in the air. more research but not abandoned. this is neat!


after a day or research, the older design seems more practical than i thought before for both cost AND perception because it is a visual difference AND mechanical may sell moreso over than an electrical design. i believe i can use a 1/4″/-4an metal braid line with the modified log splitter valve as before. i would use a two piece oil pan with a drop out center plate so i can fab the lines to the steel plate. the original had brass fittings they may be swapped for steel, welded, then faced on a lapping machine for proper seal to the case. omit the oil filter and tap the oil pick up and modify a chevy engine pick-up to weld to the tapped case pump pick-up tube.

the electrical design is not abandoned. i think the proven product and method to do this would be a custom aluminum valve body with milled passages and drilled for two spool valves. a mid plate is a definite in this design to isolate the passages. i would use two solenoids out of a 4L60E. i believe these fire an oil charge at a valve to create shift. i think if i can use an existing valve out of either a 4L60E of 4L80E then mill the aluminum to fit the passages it would be the most cost effective. exhaust each out the top(bottom to sump)/ deadhead pressure when not in use to line. basically two 3-way spool valves. as for an arming switch it would be nice to have a switch to arm the panel and dissengage park. a biondo type solenoid to go in and out of park would be ideal. so when you arm the panel it energizes to dissengage park while arming two switches for forward/reverse. this would require a 3 wire plug though. it would be much simpler to omit the park but it is a liability concern. perhaps a pinion brake with a park pin is a better option or a pin engagement to a nerat yoke.


First/Reverse only Transmissions

First/reverse only is a concept that has been around in demo derby for years and years. i remember walking around in the pits with my dad talking to people back in the 80’s as a kid. they modified their stuff for first/reverse only….or had a transmission shop do it….along with water in the tires……and running all thread instead of wire and chaining the hood. Anyways, when i started out to build a first/reverse only transmission(which started as a wager), i wanted to not only keep it from shifting, but eliminate moving parts. in essence K.I.S.S.(keep it simple…..stuipid).

the actual modification to prevent shift is actually rather simple. you unplug the modulator valve from engine vacuum and disable the governor. modulator valve is low speed shift control. governor drives just like a speedometer off the output shaft.  on both the th350 and th400, line oil pressure from the pump is supplied to the gear drive end of the governor. as road speed increases, weights fly out in a governor action working against supply oil(instead of a spring like an engine governor would work). the faster you go- the more signal oil is let by. this signal oil is then sent to the 1-2 and 2-3 shift valves. the tension of the springs in the valving controls shift point……and the size of the holes in the mid plate control how fast the gear applies.

on a th400, my method for disabling shift is to remove the governor and both supply lines entirely. you then drill and tap the oil supply port at the rear of the valve body which is meant to supply the governor. you leave the signal oil/return port open. this does two things: you line pressure is not lost anywhere in the governor circuit cause it is essentially completely removed. the other is there is no bleeding past of the fluid on any of the valving that may eventually build up and try to trigger a shift. if you are familiar with case drain on a hydraulic system, in essence that’s what it is.

Now, after298116275 the fact i figured out that by simply modifying the governor to stay closed would give you the same effect. contrary to what anyone claims, i had 15-20 transmissions running successfully in events across northern IL before i ran across this modified governor from a builder out west. it does work but it would still have the effect of wanting to shift into 2nd at high speed. here again this was caused by case drain effect. so i discovered people sticking clips into the 2nd gear shift valve. i never did this on anything i built. in fact, i use to modify my pile of old governors and sell em for a few bucks at shows years ago. this still works on th350’s and th400…….just not as effectively as my method. i would say this is about 85% effective whereas the other is 100%.

The other part unique to my 1st/reverse design is locking in the first gear holding member. on any automatic transmission to get gear reduction you have to have one holding member and one driving member to get what is called planetary action. on a th350 it is a piston style holding clutch to the rear of the case. on a th400 it is a rear 3 rib band on the front planetary gearset. a 727 also uses a band if i remember right. anyways,on both the 350/400 transmissions, reverse and 1st gear are the same gear-powerflow. the forward clutch drives first gear, while the forward clutch releases and the direct clutch is engaged to drive in reverse. so i reasoned that by permanently anchoring the holding member you not only eliminate moving parts but ensure the gearset is held. you also reduce friction and strain on your first gear holding sprag.

on th350 transmissions, i tried many different methods of doing this, as well as my friend Jim. it was hit and miss one trans would win derby after derby….the other wouldn’t pull out of the driveway. after a ton of thought i realized what was happening and found the fix, but elected to quit building th350 for demo derby cause i started seeing gearset damage and snapped output shafts. for this reason i quit building th350 for derby specific. i will rebuild one and use the 4L60 center support …..you can use it for whatever you want after it leaves my shop and it will work!

on a th400, i had much more luck. just find a way to lock the rear servo completely engaged so the the rear band doesn’t dissengage. the picture to the right was my first attempt at figuring this out using a modified rear servo cover and a hommemade adjustment screw. i then removed all the seals and pistons from the bore, plugged the oil ports off, and set the tension on the rear band manually. this didn’t work out at all…..it sucked royally. so i took a different approach to it entirely.396007827 it happened qute by coincidence i had a GM 8.5 rear end i was setting up in the shop at the same time…..looked at the servo……looked at the shim kit of that rear axle……and that worked. i eventually abandonned the idea of blocking off the oil ports to the rear servo and ended up suing the stock rear servo/accumulator with new seals but both return springs removed. you then use shim washers to shim the piston down in the bore to tension the rear band. HOWEVER, i also discovered this is an adjustable thickness of shim. there are 3 different pins used on the rear servo all different lengths….and you also have wear to the fron planetary and rear low 1 holding band. i have used a specific washer from lawson products, and on average you use 2-3 washers….sometimes one.

the most successful way to set the rear servo/band tension like this is remove the rear servo…….remove both both springs and seals ….set the accumulator on the bench…..then reassemble it back into the bore. you then stick about two washers under the servo cover and press down to the case. you want the servo cover to barely hover above the aluminum case. if there is a giant gap there it is too much. if there is no gap and you don’t feel the tension on the band……you need more washer/shim. when you get it where you want it, you then install your seals, the inner accumulator, shim washers selected washerand torque it in.

Now, it is very important that you do not overload the rear servo tension. you are suppose to prevent movement moreso that set tension. you are still getting oil flow to it in low 1/rev for holding. what we are doing here is preventing it from dissengaging fully causeing friction/heat. it will still move slightly even when shimmed. if you overtension it, it will warp the case and even screw up how the whole planetary gearset rides in the case/center support. i showed several different people how to build my style 1st/reverse only. pictured here to the right is precisely how not to do it. the 3/8″ washers will float around against the rear servo cover and your apply will jump all over the place. you would be better off just running a stock rear servo set up over this. the yellow spring works out quite well for rear servo return/accumulator springs.

There are numerous other small things i do to my derby transmission builds, and they all kinda work together. first/reverse only in my opinion is somewhat overrated in modern demo derby. with these huge geared rear axles and what not, you almost need more than one gear. and for a wire car it is a bit overkill for what your going for. a properly built stock th400 transmission driven wisely and maintained properly can win any derby, and have. the whole object of going 1st/reverse only or 1-2/reverse manual shift is to add longevity and performance to a transmission for a performance edge


360 Modular Brace for TH400/Mid-Plate Pan Bracing

Years ago i came uS3700012p with the idea of putting in a mid plate between the oil pan and the transmission case. On a th400 aluminum transmission case, they can be prone to breaking at either the rear tail shaft housing or just up from it off of the locating lugs for the rear band. When the shifter is mounted off the back of the case, it becomes a weapon next to you if the rear of the case lets loose. i had 2 or 3 friends take one hell of a shot to the legs when it happened. So, by adding a plate off the 13 oil pan bolts to the rear 2 tailhousing bolts/ transmission mount, it prevents the shifter from comming over and nailing you.

of course, this has evolved into a complete underbracing solid steel oil pan. you then add a rear tailhousing plate and build gussets from the steel oil pan to the rear tail plate. in this picture to the right is a finished mauler brace pan. i named it mauler cause it reminded me of wolverine’s claws that shoot out of his hands. on this one,  i did not use a rear plate. i elected to drill and tap the tailhousing  so i could bolt the pan brace from beneath. this allowed a 4X4 crossmember to butt up to it and use a port-o-power to wedge it into the car.

there are some plus’s and minus’s to this. you have to use allen head screws to make everything clear. it ends up about a 4 quart capacity but has a smaller depth profile than the deep sump th400 truck oil pans.  it is damn near bulolet proof, but when you finish welding it up, it can be a complete pain in the ass to get it to seal at the pan gasket. also it can be a pain to remove for simple service. i highly recommend running good old dexron II/III and servicing your trans frequently. i would pull the drain plug after every run and change out the filter every 3-4 events…….or once a year. by circulating in 3-4 fresh quarts every run it keeps your fluid juiced up…..so to speak.

what a lot of people forget though is that those big nerat bell housings have a tendency to want to pull upward and off the front of the aluminum case as the car noses up. even with top bracing….it can still pull the bolts. simply drilling and installing two bolts to the bottom of the bell is all you need(also pictured). all it is doing it keeping the bottom of the housing from moving forward. think of it as a safety strap.

now with the big push of people either going back to more stock builds or selling out completely, i decided that htere has to be a more simple and easy way of doing this other than the freaky warlord monsters i have built. so i came up with a spider bracing plate. it fits over the stock oil pan with an access hole to pull the drain plug, so there is minimal sealing issues of fit problems from welding. it can be removed without dropping the pan and is able to be removed without battling your rear bracing plate/top bracing. it is bolted to the housing and the rear bracing plate.

you then run 4 tubes cross the top for your top bracing. you can build one of these elaborate spider’s web looking things for a top brace(i have), but i have had successful builds out there wil as little as four 1/2″ I.D steel pipes from rear plate to back of the steel housing. the distributor protector and/or the nerat housing takes most of the abuse of keeping the nose down on the car. your bracing is there to keep the aluminum case in tact. the nice thing is that this set up is easy and straight forward, cost effective, AND can be removed in pieces to comply with different rules. i mean you can remove all of it and swap on a J.W. Performance bell housing for a stockish approach……or drop the bottom spider brace plate if no skid plate is allowed at the track from under the car……or you are 4-6 hrs from home and something grenades in the transmission and you need to swap in a different center unit into all you bracing.

Simple TH400’s are not so simple

when it comes to a turbo 400, as transmissions go, it is a fairly straight-forward 3 speed beast of an automatic transmission, with a fairly simple design as automatics go. produced from 1964-1991, it is largely obsolete for street use by modern standards, leaving the th400 basically either for classic cars or performance use. now there is this myth that all th400 were basically the same and the parts interchange. this is not exactly true, although if you look in any parts catalog or on-line source you would get that impression. for the most part anything from 71-87 will interchange, and thats a large chunk.

to start at the drive clutches: there is somewhere around 18 different pistons that could have been used in the forward and direct clutch packs, 4 different direct drums, three different styles of clutchs produced by 3 different manufacturers, and around 3 different types of steels in both kolene and regular steel(6).

now to keep going, there are two types of center supports, two different pressure regulators, up to 9 different ways you can mix and match up different pump halves for the front pump(some aren’t correct), 3 different case designs at the hydraulic circuitry,two different forward hubs,two different mainshafts, 2 different valve bodies, two different int pistons, 3 different accumulator pistons, 3 different pick up tubes to the filter just for the shallow pan, and two different pump gear designs. these are all the differences that you cannot see from the outside.

doing a quick math check, this leaves us with the possibility of somewhere around 20,150,000 different possible combinations of how a th400 can go together internally-not including aftermarket parts.

now, for the most part if you tear down and rebuild a th400 as an individual unit and take your time using all the same parts that came out of that particular unit, replacing stuff as necessary, there is hardly ever a problem. when you start tearing down multiple trannys at the same time and build parts ahead of time, this is where the fun begins. the thing you really got to watch above all else is how you pack your forward and direct clutches. too tight and you burn up the trans prematurely- too loose of a tolerance and parts will have a tendency to smack together and break the backing plates…..and worse yet certain clutch to piston combinations can snag the steels and keep it from applying all together.

for arguement sake, lets leave the clutches and steels out of the equation: there is still nearly 72 different ways to screw up mixing and matching up how you put together your pistons and drums. ok lets say you pack your foward and direct clutches ahead of time to be ready for a customer. you take his chevy 400 truck trans apart, simply grab a ready to go packed forward clutch off the shelf and put it back together. it went together fine right. but by mistake you grabbed a forward drum out of a 65 caddy trans with a large drive hub and you have a late model gearset. oops. you will be destin for an angry phone call.

Transmissions cannot and should not ever be mass produced. you have to treat them as you would treat a performance engine build: as an individual beast. even though you can go fast you have to take your time and be purposeful in how you build. it is a mistake that i made early on myself, and i watch shops do it all around me these days. when i started building newer transmissions i slowed down and was more meticulous in how i build. i then went back and took the same methodology to a th400 again and i tell ya what, i think it really made all the difference in the world. moral to the story: Don’t ever sacrifice craftsmanship for profit, it will bite you in the ass in the long run.

now a th400 is relatively a simple design, they get worse/more complicated from there.

2 Piston rings Vs. 3 Piston Rings

Here is my take on 2 rings vs 3 rings-
A typical ring system works like this…
top ring: Sealing and heat transfer.  This ring is what seals the cylinder on the power and intake strokes.  It also transfers heat from the piston crown to the cylinder wall and cooling system.  The ring groove in the piston has a huge impact on how well this all works.
middle ring: Oil removal…period.  The middle rings sole purpose is to remove oil from the cylinder wall.  The taper face design of most middle rings is not suitable for sealing pressure and is expressly designed to remove oil on the down stroke.
bottom ring: Oil removal.  This ring removes the bulk of the oil from in between the piston and the cylinder wall.  The ring tension and return holes in the ring groove will determine how efficient this ring does its job.
In a 2 ring piston you loose much of your oil control ability because you have removed your middle oil scraper ring.  This has no effect on sealing because that is the job of the top ring only, and you still have that one in place.  If you have chamber oiling issues due to the lack of a middle ring and have to increase the bottom ring tension, you will likely end up with more drag than a properly designed 3 ring system.  A reduced radial thickness middle ring, such as a Napier style ring, produces very low drag on the cylinder but removes oil very effectively.  This allows you to lower your bottom ring tension and end up with a ‘dry’ ring package that has fairly low total drag.  Best of both worlds there.
One application I know that uses 2 ring systems successfully is high performance 4 stroke motorcycle engines.  The oil system in a modern 4 stroke motorcycle is far superior to a V-8 engine.  This results in less oil for the piston to deal with and the opportunity to remove a middle scraper ring with no adverse effects.  V-8 engines with large crank strokes and poorly designed oil management result in a large amount of oil flying around in the bores and on the pistons.  This situation requires more effort to remove oil from the cylinders to keep it from the chambers.
For a 2 ring package to work well, in my experience,  a very good oil system is required as well as an engine that can tolerate some oil in the chambers.  And there just isn’t much you can do to help the oil system in a V-8 unless you go to a very efficient pan and multi scavenge dry sump system with lots of vacuum.  Even then it is not as good as the motorcycle design. If you end up with a 20-25lb bottom ring to pull double duty,   why not just use a 6lb bottom ring and an .043×145 napier middle ring.  That would have less drag that the 2 ring combination.
I’m not sure what the high end guys are really doing but I can say that I will be sticking with .043-.150 to .170 top rings, .043-.145 napier middle rings, and 3.0mm 6-8lb bottom rings for our drag race stuff. Even .8mmx.8mmx2.0mm has been working great.  I don’t see myself revisiting a 2 ring design anytime son.
If you are going to try this approach I would suggest using a normal top ring deal and bumping the bottom ring tension up a bit, maybe even going up in size.  .043 top x 3/16 bottom perhaps?  Use a vacuum pump, build a good oil pan with a kickout & scraper system, etc.  Might increase your results with all those thing aiding it along.
For many years CAT ran a two ring (single compression ring) piston on the 3208 diesel engine. The top ring was a keystone design and the oil ring a one piece cast ring with a spiral wire expander.
There were many, many thousands of these engines produced in both NA and turbo, with compression ratios as high as 20:1 on NA engines. When maintained, these engines gave good service life with this ring package.
Bingo.  Notice in this example, the second ring is a rigid device, not the loose wipers normally found in 2 ring “gas” buring/spark plug ignited engines.
I can only speak to my experience.  In power adder engines, the lower the radial tension of the second ring the worse the hp, blow by and overall oil control.  Keep in mind i never go larger than .043 on the second.
The best experience I have seen is with a Total Seal CI second ring with a fairly big end gap.  Close up the end gap too much and everything starts to go south.  Open up the end gap and everything gets better to a point, then too much end gap hurts too.
The only thing I can figure out is, the second ring provides a cushion pocket for the blow by coming past the first ring.  If the second ring has too tight a seal, then blow by gas (what I consider windage at this point) builds up underneath the top ring and unseats it.
Also, if the second ring has too loose a seal, the the blow by shoots in all directions once it clears the top ring (again, I consider windage at this point), again, unsettling the top ring some.
-All of the serious engines I have built I have used the two ring deal. The piston makers do not like it, but most of these engines made quite a bit more power than they should. I know there is a lot of HP in the gas porting, top ring package, and the vacuum pump. I like to do things that noone else does. I like real big cams too.
JOE SHERMAn racing engines
I will not dispute anyone’s advice on this subject. Years ago Manley marketed a piston called the S.R.T. (single ring type). T.R.W. also offered a single ring piston. It never caught on, be it, resistance to change by engine builders or it just didn’t work. The top was genarally a head land design. The head land was basically a big dykes ring with a special expander behind the ring and the top of the ring was square to the piston flat. It was a concept that in which it’s time hadn’t come. It also had a 3/16″ oil ring. Engine builders would use them, but the diehards, would use a1/8″ oil ring coupled with 1/16″second ring in the oil ring land. In essense defeating the purpose. At that time rod length and or large C.I.s was not an issue. The theory of the time was positioning the top ring as high as possible to promote cooling. The ring face was larger than a 5/64″ ring, with low radial tension and an expander was put behind the ring. To reduce drag the second ring was eliminated. The .043 top ring and gas ports were also being experimented with. When the smaller ring proved more beneficial for high RPM applications with the conventional 3 ring package. The head land 2 ring design fell by the wayside. With todays ring and piston technology along with large C.I.’s it might be time to rethink the 2 ring design.

Performance Engine Theory


 so in my working with my 4.3 project, i ended up re-using the factory roller camshaft. the lift on it at the valve during dial in was a .346 on intake and a .382 on exhaust with a 110 lobe center. this was a really mild spec, and my only estimation was that the factory is using hyd roller lifters for longevity more than anything else due to the lack of additives in modern engine oil. a high zinc content is necessary in engine oil for prolonged flat tappet camshaft life…..which has been removed from most engine oils due to both cost and emissions.

but i had to wonder about it cause it’s bugged me for years…..these camshaft specifications were ungodly similar to a specialty derby use cam someone conned me into buying years ago. so i re-visited an old project with a different perspective.

 so i dug through my archives…..and dammit if it wasn’t dead on within .003″ lift at a .050″ spec. the durations however were much different. the cam in question i got was a much shorter duration intake and a much wider duration on exhaust than this stock spec on this 4.3 cam i have now…..which also resulted in a tighter lobe center at 108 deg. lack of fuel: more exhaust- explains the lack of power while also giving you the illusion of having a performance cam due to the tight lobe center. overall result is a cooler operating temperature.  i don’t think the cam is very critical per say as far as the specs more so than the advantage is the roller valvetrain over a flat tappet..

 but the funny thing is, i think it is only a piece to a 3 way puzzle. i have come to the conclusion that reducing piston ring tensions is also key whether or not it is by running an extra .010″ of clearance on your piston to wall spec or using a set of low tension claimer rings. perhaps even omitting one of the compression rings and/or using a single total seal compression ring .  

the third piece to the puzzle is crankshaft clearances. Bill Trovato has justified the logic behind the extra clearance on the low end of the block due to flex in extreme conditions……such as drag racing. block flex is a major plague of big block olds engines. in the case of derby the extra clearance is moreso for heat expansion AND reducing friction. this is also explained obviously by the need for some builders to use ungodly thick oil additives with 20W50 motor oil.

now, this 3 way puzzle to a derby engine: have i actually done it to a gen 1 or 2 chevy v-8 yet and done any testing…..no. will i…..likely no. would it work….most likely. i do know that each of these three principles are in practical use by several reputable engine builders across several motorsports.

 i also researched a bit into the 5.3 and 6.0L iron block vortec/LS engines. most of the issues i listed above have already been remedied already from the factory as far as roller valve train, piston ring tensions, and block flex. not to mention an incredibly efficient oiling system. so that’s the direction i am going if i decide to spend money on another SBC build for myself.

Chevy 4.3 liter build Pt. 2: teardown and parts search

well, the first thing i did armed with a bit of knowledge and the core i had is to commence teardown and assessment of what i really had. i was actually pleasantly surprised at how well the engine really looked. it was a high mileage engine out of an early 90’s S-10, and i had narrowed it down to a 91-92 vintage plant. this was a TBI engine with a remote oil filter set up, factory hydraulic roller cam, and non vortec heads. the timing cover was identical to the common older style i was looking for. the goal here was a 4.3 that appeared to look like an old school 70’s v-8 350 chevy. i have to admit, it took a bit of imagination to see it under all the electronic injection, emmissions, and serpentine belt stuff. all the accessories unbolt right off.

with any high mileage engine like this, the timing chain is shot and it was loaded full of varnish. it looked like it had ran hot for a long period of time so it probably had a bad oxygen sensor and/or a terrible state of tune on the ignition causing major carbon deposits on the cylinder head runners. after removing the heads i saw i had a slight dish piston with valve reliefs. the rods and mains were for the most part unmarked, so for ease of re-assembly i marked em like i would with an olds v-8. anyways the crank had seen better days, but was undamaged. it is quite possible i have the heavy duty romulus mfg crankshaft but i don’t know for sure….and don’t really care.

the real killer for me was the cylinder wear….about .010-.012″ of wear in the top of the cylinders leaving a ridge…..which i reamed off. after weighing out parts kits, and machining costs, i came in at around 2500$ to do a relatively standard build with a descent cam. i priced a GM goodwrench longblock identical to it for less than 1800$, so it didn’t take me very long to figure out that unless i wanted to overbore and build something really hot nutz, there is no point in a standard build. BUT, there was enough left of it i decided to buy a rering kit and have some fun with it.

the re-ring kit with gaskets,main, and rod bearings came in at around 210$. i went with an edelbrock intake at just over 200$. i had a set of taylor wires already(55$), and built the distributor for about 40$(as detailed in another post). the oil filter needed a mount, and i found a threaded arbor out of a junkyard for buttkiss. it simply threads into the oil filter location at the rear of the block and is removed/installed with an allen wrench to the center. i got an edelbrock performer carb off ebay for 75$, and i spent 30$ on carburetor cleaner and brake clean to clean all the parts.

now in listing pricing and parts, i must also mention that to simplify the approach to ordering parts, i consider there to be two major groups of these 4.3L engines, and the major design break is in the 1992 area. 92 and older engines similar to the one i have are more like an old SBC with the oil pump, cylinder heads, and timing chain cover interchangeable with a v-8……and no balance shaft. in addition the intake pattern is also the old style with an angle.

92 and newer engines they added a balance shaft, went with vortec heads(which also changes the intake pattern), changed the timing cover style, changed the oil pump parameters, and in the early 00’s even the bell housing and oil pans were unique. basically…..the newer you get:the more expensive it is.

even with these two major groups when it comes to ordering parts, i also discovered that they offer both shallow groove and deep groove oil rings for the same year same mfg engine. there is no way of telling what you have unless you physically micrometer the oil control groove ring for depth on your pistons. i attempted to use the rings that came in the kit and after arguing with the summitracing tech for an hour….and getting a piston stuck during re-assembly…..i ultimately ended up using the old oil control rings with the new compression rings in the kit. also you can only get moly top ring kits for the 4.3 and can run from 65-85$ a set. if i was doing this over again i would have bought a cheap v-8 set of rings for 25$ and simply robbed out what i needed. so the moral to the story is micrometer your pistons before you make an order.

in my case to finish this part up, i got a factory roller timing set for 37$, and in my case could use a good old common sbc oil pump for 20$. the grand total for this little learning experience was around 850 bucks including the core fee i paid at the yard. i have yet to buy some pipes, but i figure i can use the manifolds up until i figure out what vehicle it is going in. although i have yet to fire it to know for sure what i will end up with, hard money i am out if it doesn’t work and go with a reman engine is actually closer to 350 bucks, and that isn’t bad at all for the learning experience i got.


Chevy 4.3 liter build Pt.1 : information

Well, i decided to start into a 4.3 v-6 for my next project. with any new project you take on, do some research first to save yourself as much headache as possible. much like when i took on learning about 700R4 transmissions and the family a trannys with it, the 4.3-and the rest of the v-6 chevy family is just as elaborate. it didn’t take much to realize the the 4.3 engines are like snowflakes….making a right core essential for what you want to accomplish. i ended up with a 92 vintage 4.3, with the older style bell housing for my 700R4 tranny to bolt on to. it does not have a balance shaft so i will have less rotating mass(more power), and it was made in romulus michigan. the other plant these engines are made in is Towadanda  New York. there is no real clear cut designation to tell what it is from. i had to take crank, block, and cylinder head casting numbers on the engine in combination with the info i tagged on below to figure out what i had. one thing that is a giveaway is that there is a “4.3” cast into the left rear bell housing boss in the location you would find the block casting number on a SBC V-8. the casting number on the block is on the opposite side of the bell housing.

anyways, it has a roller cam in it and a metal retainer tray that resembles that of a votrec v-8. later models used plastic……so in essence i feel like i am starting with a great core. i have yet to tear it down completely.

unlike the v-8 small block chevy, the 4.3 has quite a following overseas.  my guess is it is due to it’s relative size and/or availability in comparison to most domestic v-8 engines. i chose it as a great alternative for a street rod cause of rising gas prices, as well as the power/weight ratio i was going for.

here is some tech info i found that may be helpful. it is quite an elaborate breakdown, i will simplify it a bit in a later post. thanx.


1985: The original block in ’85 was a 14071177 casting. It had a two-piece rear seal, a flat tappet cam and a fuel pump hole because all of the trucks still had carburetors. Just for the record, there were some ’86 blocks shipped with pans for ’85 service replacements, so it is possible for a customer to have an ’85 car or truck with a one-piece rear seal.

1986: In 1986, the block (c/n 14088553) was modified to accommodate the new one-piece rear main seal. The fuel pump hole was still open, even though it wasn’t always needed, because all of the cars and some of the trucks came with throttle body injection.

1987- ’94 WITHOUT BALANCE SHAFT: In 1987, a roller lifter cam was installed, so the block was changed again. Two bolt bosses were added in the middle of the valley for the lifter retainer that kept the rollers properly located on the cam and perpendicular to it. This same basic block was used through ’91 for everything, and in ’92 through ’94 for all of the engines without balance shafts except for one small difference – some of the blocks came with four bolt holes for the tunnel style retainer beginning in ’92. There were several different castings used, including the 10105867, 10172756, 14099073, 14093683 and 10066011 with the two-bolt retainer, and the 10172756, 14099073 and 10066061 blocks with the four-bolt retainer.

1992 WITH BALANCE SHAFT: The L35 balance shaft engine was introduced in ’92, so the block was modified to make room for it above the camshaft. The lifter retainer was changed to the tunnel design because of the balance shaft; it had two bolts on each side instead of the two in the middle.

There were two versions of the balance shaft blocks in ’92. The “first design” block had a needle bearing on the back of the balance shaft that was lubricated by the oil mist from the valley. The “second design” had a sleeve bearing that was pressure fed through an additional drilled passage in the back of the block.

All of the 1992 “first design” (c/n 10105903) and “second design” (c/n 10224834) blocks were missing the two bolt bosses, one on each side, that were used with the reinforcing struts for the automatic transmission on some of the ’93 and later applications, so they can only be used in ’92. Be sure to double-check the 10224834 “second design” blocks, though, because some of them came with the strut bosses in the later years so they can be used for the ’93s and ’94s.

1993-’94 WITH BALANCE SHAFT: Things got more confusing with the balance shaft blocks in ’93-’94. All of these engines have to have the two extra bolt holes for the strut bosses and 10 bolt holes for the tin front cover. See photo. There are five castings that may or may not be right:

•All of the 10224534 and 10224535 blocks have the two strut bosses and 10 holes for the front cover, so they will fit everything in ’93 and ’94;

•The 10227196 castings have the strut bosses, but they came with either six or 10 holes;

•The 10224834 blocks have 10 bolt holes, but they came with or without the strut bosses;

•The 10235359 blocks were the most confusing because they came with or without the two strut bosses and with either six or 10 holes for the front cover!

Consequently, all of these castings must be checked and sorted by both casting number and features in order to be sure that they will work in everything in ’93 and ’94.

1995 WITH BALANCE SHAFT: 1995 isn’t a whole lot better. All of the ’95 engines had a balance shaft and the strut bosses, but the flange around the timing gear was changed to accommodate the new plastic front cover. The overall shape stayed the same, but the flange was noticeably wider with big bulges around six of the bolt holes. See photo.

There was a mid-year change that can cause problems, too. The early engines used a “first design” tin front cover with 10 bolt holes. The later ones had the “second design” plastic cover that had only six bolts, so the flange can have either six or 10 holes drilled in it. See photo. That means that the tin cover won’t work on a block that was drilled for a plastic cover, so the blocks aren’t always interchangeable.

Things can get confusing in ’95, because the 10227196 and 10235359 castings that were used in ’95 came with the narrow flange in ’94 and were converted to the wide flange in ’95. All of the 10227196 castings had the strut bosses, but some of the earlier 10235359 castings didn’t.

You can use either one of these blocks in ’95 as long as it has the strut bosses and the wide flange with either six or 10 holes drilled for the front cover. But, you must be sure that the corresponding first or second design front cover is installed on the block.

Given the possible confusion over which cover the customer has and which block he really needs, it’s probably better to make sure all the blocks have 10 bolt holes so they will work with either front cover. Do not use an earlier block with the narrow flange with a plastic front cover under any circumstances because it will leak oil.

1996-’98: The block was changed again in 1996. Structural reinforcing ribs were added on both sides of the timing cover and both sides of the block were contoured to follow the shape of the cylinders more closely. See photo. This one is a 14099090 casting. This same block is used up through 1998.
There is one other subtle difference in the blocks. The cam bearing sets are different, depending on whether the block was made in Romulus or Tonawanda. The Tonawanda blocks use two larger diameter cam bearings, one in front and one in back, instead of only one large one in the front. Both bearing sets are available in the aftermarket.
There are three characteristics of each block which will tell you where it was manufactured:

•If it’s a Tonwanda engine, it will have a “T” stamped on the machined surface on the block just in front of the right cylinder head. The engine ID will be number stamped on the pad, and the chamfer on the cylinders will be quite shallow;

•If it’s a Romulus engine, it will have an “R” stamped on the machined surface on the block. The ID number will be made up of a series of dots, and the cylinders will have a deep chamfer on them.

Some of the blocks are drilled for a knock sensor and some aren’t. It’s almost impossible to know which applications came with and without the sensor hole, so most rebuilders drill and tap every block so the hole is there when it’s needed.


The roller cam motors have used three different lifter retainers. All of the ’87 through ’91 non-balancer blocks and some of the ’92s used a flat retainer (p/n 10046165) with two bolt holes in the middle. As of ’92, all of the balancer motors and some of the non-balancer motors came with the tunnel-shaped retainer (p/n 10105916) with four bolt holes, two on the outer edge on each side.

Starting in ’94, Chevy used two plastic retainers (p/n 12551431) that are bolt-in replacements for the tunnel-shaped version. There are some later intakes that will hit on the reinforcing ribs on the tunnel-shaped retainer, so it’s best to use the plastic retainers in all of the blocks that have the four bolt holes.

Chevy has used several different cranks in the 262. They came with one- or two-piece rear seals and in both light and heavy versions that were specific to each engine plant. Here’s an overview:

1985: The 1174N casting came with a two-piece rear seal and a flange in the back. See photo.

1986-’87: The 14088640 and 10105865 Tonawanda castings with a one-piece seal were both used only for heavy applications during these years. See photo.

1988-’98: The Tonawanda cranks were all 10105865 castings that came in both light and heavy versions.

1988-’98: The Romulus cranks were all 10055480 castings that came in light or heavy versions.

All of the engines with the one-piece seal were externally balanced with specific flywheels and dampers, but the cranks were also balanced according to the weight of the pistons and rods that were installed in the engine; it’s important to use the right combination of parts. Unfortunately, there’s no sure way to tell a light crank from a heavy one short of knowing where it came from and marking it at teardown or spinning it on a balancer. There are a couple of clues that can help, though:

•All of the 14088640 castings are heavy cranks that can be used in either the ’87 to ’94 non-balancer engines or in the ’93 to ’95 VIN “Z” balance shaft motors with the heavy pistons.

•If a 10105865 Tonawanda casting came without a hole in the first rod pin, it’s definitely a heavy crank. If there’s a hole in the first rod pin, it’s probably a lightweight crank. However, there were a few early 10109865 cranks that had the hole drilled in the rod pin to correct the production process, so having the hole drilled doesn’t always guarantee a lightweight crank.

•The 10055480 Romulus crank came both ways, too. If it has a hole in the first rod pin, it’s the lightweight version, and if it doesn’t, it’s always a heavy crank.

The heavy cranks were used in all of the engines without a balance shaft and in all the VIN “Z” balance shaft motors with the heavy pistons, including the ’95 “second design” versions. The lightweight cranks were used with the lightweight pistons in the ’92-’98 VIN “W,” the ’95 VIN “Z,” “first design” engines, and in the ’96-’98 VIN “X” engines. Using the right crank in the right engine will help prevent balance problems out in the field.

However, you should also be aware that all of these engines are externally balanced with various combinations of flywheels/flexplates and dampers for balance, and that they are “trimmed” at the factory after the hot-run test by pounding balance weights into the holes that are already drilled in the damper. So, if you build them right and still have a shaker, the customer will have to add or subtract weight from the damper and/or flywheel/flexplate in order to get it right.

There is one other subtle difference in the cranks, too. Any of the engines that were installed in ’96 or later and all of the ’95 “S” and “T” trucks with OBD II, including all of the Olds Bravadas, any Blazer with California emissions, and about 10% of the Blazers with federal emissions, had a reluctor wheel installed in front of the crank gear for a crank position sensor that was a part of OBD II. The raised, machined area on the snout is about .100? longer on these cranks than it was on the earlier ones so the reluctor wheel has a slight press fit. Be sure to sort out the 10105865 and 10055480 cranks with this longer, machined step and save them for the engines that have the crank position sensor.


There are four different rods in two different weights that come from two different engine plants, so there’s plenty of room for confusion, but it all works out if you follow these two rules:

Rule 1: Keep similar rods in sets by both appearance and weight;

Rule 2: Use only Romulus rods with Romulus cranks.

Then, the question is, how do you tell them apart so you can follow the rules? Start by sorting them by engine plant based on the shape of the balance pad on the big end. If the rod has a cast pad that’s only machined on the face, it’s a Tonawanda rod. These rods don’t have a forging number and may or may not have a dot on the shank.
If the weight pad on the big end is long and narrow and has been machined on all five surfaces including the sides, the ends and the face, it’s a Romulus rod. All of these rods will have an 818 or 045 forging number on the shank so they’re easy to identify.

After you have separated the rods by source, sort them by weight and put them in sets. The lighter ones will weigh around 662 grams, and the heavier ones should weigh about 675 grams.

The light and heavy rods can be interchanged in engines in sets, but it’s best to use the Romulus rods only on Romulus cranks because you may end up with a ticking noise if they are used with a Tonawanda crank. The Romulus rods have a wider face adjacent to the parting line that can hit on the side of the split pin rod journal, so the Romulus cranks are machined to provide additional clearance for the rods.

The Tonawanda cranks aren’t relieved in this area, so there can be light interference and a noise problem. The Tonawanda rods have the narrower face at the parting line so they can be used with either crank.


There have been five different pistons used in the 262 along with two versions of the lightweight piston.

1) The original, heavy piston used in the 262 was the same as the one that was used in the 350 V8 except that the pin boss was opened up slightly for the offset rod. It weighed about 745 grams with the pin and had a 9.1:1 compression ratio. It was used in all of the light duty engines without the balance shaft from ’85 through ’94 and in the VIN “Z” balance shaft motors from ’93 through part of ’95.

The parts catalog identifies the ’95 VIN “Z” engines with this heavy piston as the “second design” version even though they were built during the first part of the year. They will have one of the following engine codes: ALH, ALA, ALB, ALC, ALD, ALF, ALH, ALJ, ALL, ALP, ALS, AJS, AJT, AJW and AJU.

2) The lightweight piston weighs about 675 grams with a pin. It was used in all the high output, balance shaft engines (VIN “W”) from ’92 through ’98 and in all the VIN “X” engines from ’96 through ’98. It was also used in the “first design” VIN “Z” engines that were built during the latter part of model year ’95, including those with the following engine codes: AAB, AAC, AAF, AAJ, AAK, AAL, AAP, AAS, AAW, AFC, AFD, AHC and AHD.

The lightweight piston was originally a Mahle, full-round design (p/n 2753), but GM switched to its own “RPM” (Revised Permanent Mold) design with a short slipper skirt and a narrower pin boss in ’95. Both of these pistons have very short skirts, so the clearance must be right or they tend to make noise at startup.

3) There was a heavy duty engine offered for trucks and vans with over 8500 GVW from ’89 through ’95. It used a heavy duty, Zollner piston that had an 8.3:1 compression ratio and weighed the same as the regular heavy piston.

4) There was also a high output, VIN “B” (LU2) engine offered in the Astro van in ’90 and ’91. It used a special, hypereutectic, strutless piston that is available from GM under p/n 10181389 in standard, or from Zollner as a H-8269-D. It weighs about 745 grams, just like the rest of the heavy pistons.

5) There was one more piston used in the 262. It’s a low compression (8.6:1), strutless, hypereutectic piston with a deeper dish that was used in the turbocharged Syclones and Typhoons from ’91 through ’93. The OEM standard piston is p/n 12508702 and the Zollner number is a H-8269-E.

All of these pistons are specific to the application, so they should not be interchanged. Building an engine with pistons that have the wrong weight or compression ratio will guarantee a comeback, so it’s better to play by the book.



Any 90° V6 creates some strong, primary imbalance forces, especially in the vertical mode. The 262 is no exception. Chevy originally underbalanced these engines by putting about 46% on the bobweights instead of the usual 50%. This reduced the vertical imbalance that was trying to lift the engine up off the mounts, but created a strong horizontal imbalance that shook the engine from side-to-side instead. So, in order to eliminate a lot of the “noise, vibration and harshness” in the engine and make it into a world-class motor, Chevy added a balance shaft to the premium engines in ’92 and included it in all of them by ’95.

There are two balance shafts, a light one and a heavy one, and two versions of the light one. See photo. The light one is either a 10224542 or a 10172748 casting that comes with or without a metal wear sleeve installed on the back journal, depending on the application. The wear sleeve was used on the lightweight balance shaft when it was installed in a ’92 “first design” engine with the needle bearings in the back, but it wasn’t used when the lightweight shaft was installed in the “second design” engine that had a bushing in the back of the block.

This “first design” shaft should not be used in a “second design” engine because the wear sleeve shortens the surface area needed for the bushing. These lightweight shafts were installed in all of the engines that had the light pistons including the ’92-’98 VIN “W,” the ’96-’98 VIN “X” engines and the “first design” VIN “Z” engines in ’95 that were built with the lightweight pistons.

The heavy balance shaft is either a 10224541, a 10105902 or a 12550286 casting. It can be visually identified by the raised identification band around the middle of the shaft. It was used in all the ’93-’94 VIN “Z” balancer engines and in the ’95 “second design” VIN “Z” balancer engines with the heavy pistons. The heavy balance shaft weighs about 125 grams more than the light one, so it shouldn’t be interchanged with the lighter one.

The balance shafts rotate at engine speed and are gear driven off the front of the cam. There are two different gear sets, one with “wide” teeth and one with “narrow” teeth. The ones with the “wide” teeth were used in the “first design” engines along with the needle bearing balance shaft. Some of these early balance shaft engines had a whine to them, so the gears were modified at the same time the block was changed over to the “second design” version with the sleeve bearing in the back. We recommend using only the “second design” gears to help avoid any possible noise problems.

There have been several cylinder heads used on the 262 since it began in ’85. Some of the changes appear to be minor, but most of them will create problems if the wrong head is used in the wrong place. Here’s an overview year by year:

1985-’86: The 1985 and ’86 engines used a 14079248 casting. It had two holes on one end and three on the other end.

1987-’91 TRUCK, EXCEPT HEAVY DUTY AND ’87-’93 CARS: These heads were the same as the earlier ones except that they had three bolt holes on both ends. The intake surface above the ports was quite narrow; it’s only about 0.250? wide. The unmachined, cast ledge on the top edge of the head was 0.600? wide. Look for c/n 14094768, 10144103, 14099067 or 12553050. All of these heads had adjustable rockers.

1992 TRUCK WITH TBI AND NO BALANCE SHAFT: These heads had a wider surface for the intake gasket even though they didn’t need it because all of the tooling was changed to accommodate the new heads for the VIN “W” CFI engines that were introduced in ’92. The 10144103 casting was carried over from ’91, but it had the wide intake with straight ports on the top. It can be used along with any of the earlier 14094768, 10144103, 14099067 or 12553050 castings from ’87 through ’91.

1992-’93 TRUCK WITH CFI, BALANCE SHAFT: When the high output VIN “W” engine with central fuel injection was introduced in ’92, the heads were redesigned for the application. They had “eyebrows” added to the top of the intake ports to make room for the injector nozzles, so the intake surface above the ports was increased by 0.250? for improved sealing, and the cast ledge above it was narrowed down to 0.350? to provide more room for the intake manifold.

The 10077626, 14099064, 10240209 or 10238181 castings were used, but be sure to check them over carefully because there are two versions of the 10238181 and 10240209 castings with an important difference. In ’92 and ’93, they came with an 8° top angle on the intake seat and a 75° throat, but that was changed to a 30° top angle with an 80° throat in ’94. Separate the 8° heads from the 30° heads and use them only on the ’92 and ’93 engines.

Tonawanda switched to “net lash” rockers in ’92, so some of these are adjustable and some aren’t.

1993 TRUCK WITH TBI, EXCEPT HEAVY DUTY: The intake manifold on the TBI motor was modified in ’93 to take advantage of the wider intake surface that was machined on the ’92 and up heads, so these engines must have the heads with the wide intake and should use the castings with the 8° top angle on the intake seat.

1994-’95 TRUCK WITH TBI OR CFI, EXCEPT HEAVY DUTY: The top angle for the intake seat was changed from 8° to 30° and the throat was opened up from 75° to 80° to give a 10% increase in intake airflow for better performance in ’94. The same heads were used on both the TBI and CFI engines through ’95.

Both the 10238181 and 10240209 castings were used, but they have to be visually sorted because the early ones with the 8° seat probably shouldn’t be used on the ’94s and ’95s. If you do decide to stretch the rules and use the ’93 heads on a ’94-’95 engine, be sure to use them in pairs. Some of the ’94s still had adjustable rockers because Romulus didn’t switch over to “net lash” until ’95.

1996-’98 ALL TRUCKS EXCEPT HEAVY DUTY: There was another all new head introduced in ’96. It had bigger intake and exhaust ports, no exhaust crossover and four angled bolts for the intake. It’s the 10235772 casting that was used up through ’98.

1989-’95 HEAVY DUTY TRUCK WITH TBI: There have been three different heads used on the heavy duty 262 since ’89.

1) 1989-’92: The original head, c/n 14099066 was used up through ’91. The 10144115 casting with the wider intake surface showed up in ’92 even though the narrow one still worked. Both of these castings are interchangeable.

2) 1993: The 14099070 casting came with an 8° top angle on the intake seat in ’93, but it was also available with the 30° top angle in ’94 and ’95. Sort them accordingly and use them in pairs.

3) 1994-’95: The 14099070 casting with the 30° top angle for better airflow should be used on the ’94 and ’95 engines. Be sure to use them in pairs. See photo.

All of these heavy duty heads had hard donut seats, replaceable guides and heavy duty exhaust valves with 3/8? stems.

1991-’93 SYCLONE AND TYPHOON WITH TURBOCHARGER: The turbo motors used the same heads that were installed on the VIN “Z” throttle body motors. It appears that they came with the narrow intake surface all the way through ’93. Look for the 14094768, 10144103 and 1409967 castings.

From ’85 through early ’93, the 262s used the regular small block oil pump with the 0.620? (5/8?) hole for the pickup tube. In mid-’93, the pump was changed because the pickup tube was enlarged to 0.742? on the “S” and “T” trucks. After ’93, all of the engines used the pump with the big hole.

There are several different pickup tubes used, depending on the application, and there are two different diameters, depending on the year and application. Be sure to check it out carefully and match them up at the sales counter if at all possible.


4.3 262 chevy distributor build hei conversion

well, the new project i have going on now is a 4.3 liter chevrolet engine build for a street rod build. since the 4.3 line of engines came out in 1985, there is no real drop in non computer controlled distributor offered ever for these engines. this leaves you with either buying a cheap chinese knock off on ebay and hope it doesn’t wipe out your cam drive gear, or spending hundreds of dollars buying either a mallory or msd distributor……or simply using an efi set up. i wanted to go old school with a carburetor and older HEI set up. after some research, and a bit or trial and error i came up with something.

now, the first instinct for anyone is,” well you idiot just grab a distributor out of a 3.8/229 chevy engine and you’re good. BIG mistake. the 200-229 v-6 engines were an odd-fire engine and unique to themselves. the 4.3 is different in that it is an even-fire engine like the 350 SBC…..and also an inline 6 engine.

the basic strategy here is to take two distributors and make one good one. we need two 70’s vintage hei distributors: one for a small block chevy v-8 and another for an in-line 6 cylinder…..the one with the ford style cap above is the factory straight 6 dist. out of a 75 chevy 3/4 ton i got from the junkyard. we are going to use the v-8 shaft, gear, module/wiring, and base. we are going to rob out the 6 cylinder pick up coil and star shaped reluctor(the pointed piece that is part of the mechanical advance) to put into the v-8 distributor.

first step is to remove the cap and rotor off both distributors. you then remove both distributor gears  using a pin punch and small hammer. the gears usually come right off. at this point you can remove the shaft/mechanical advance assembly but it usually gets stuck about half way out. pull the shaft half way out and if it begins to bind, stop and shoot some carburetor cleaner into the base. it breaks up the oil varnish and usually will allow you to remove the shaft without forcing it. don’t get the brilliant idea to pound on it with a punch as the dist is soft material and will disform. with the shaft removed from both units, set them aside. now take your v-8 distributor and remove the pick up coil from the center. it has a small clip retaining it in the center. notice it has 8 points here in the picture….for 8 cylinders. this is what signal’s the module to trigger spark. we are going to install the pick up coil out of the 6 cylinder distributor in it’s place that has 6 points…..so go ahead and do that…..and your base is ready. also as a side note, you usually want to use the vacuum advance off the v-8 as it has more range of travel than the in-line advance

next, we have to remove both reluctors. it’s pretty simple, just remove your advance springs, outer weights, and you expose two c-clips. pop these off……and they like to fly so be careful…….then the center cam comes off. you may have to coax it to get it to come up and off. once all the upper hardware is removed from the shaft, the reluctor assembly should be able to be removed. set the v-8 stuff aside and remove the reluctor assembly  from the inline 6 set up in the same way. install the 6 point reluctor on the v-8 distributor shaft. assembly is reverse of the tear down and is pretty straight forward. when re-assembling the distributor take note not to forget the thrust washer between the distributor gear and the base housing.

now, for a better view of what to expect, to the left of this picture is your v-8 reluctor and rotor, to the right is the in-line 6 reluctor and rotor. it has two extra support tabs on the right, but there is no worried, these rotors and reluctors will interchange. HEI distributors came with or without the extra support tabs on the reluctor. you will also notice that the v-8 base has 3 wires comming out of the base electronics and the in-line 6 has two. well, the middle in-line has an external coil, allowing for the flat ford style cap. the extra wire on the coil-in-cap set up in the center wire(black) and is for grounding the coil, which is unnecessary on an external coil set up. if you are going to run a large carburetor like a 4150 holley on a 4.3 engine, you may want to use the inline external coil and flat ford style cap for clearance(along with a carb spacer too).


however it does not onto a stock tbi intake unless you remove the egr valve…..which is a mute point as if you are going to use one of these ignition set ups you will probably not be trying to use a tbi intake. they did however make 2g marine intakes for these engines, and edelbrock makes a nice afb/holley square bore intake manifold for the 4.3, which is going to be used in this case.


4L80E Transmission Facts

Rather than do an end to end anal exam with this transmission, i have to be honest…..compared to servicing a 4L60E this thing is not bad at all. if you can do a Th400, you can do this thing. for the most part it even shares the same gear ratio’s as the th400, reverse being a slightly lower ratio over the 400 though due to the overdrive unit.

first gear: 2.48:1

second gear: 1.48:1

third gear: 1:1

fourth gear: 1 :.75 – overdrive

Reverse: 2.08:1

 i am going to go over some of the things to look for and be aware of durning your build. most of these are outlined in your ATSG book. the first thing is that the later model transmissions were a different bell housing to accomodate the LS engine bell housing. the easy way to tell is it has the extra bolt hole at the top of the housing that older bell housing pattern housings did not have.

Starting at the front,S3700038 the overrun clutch assembly on earlier model trannys was known to be a problem area. in 2001 they changed the design of the overrun roller clutch assembly due to wear issues with the sprag. the new design set up can be retro fitted into older transmissions, however when they changed the sprag, they pretty much changed damn near everything you see in this picture to accomodate the change, including the input turbine shaft.



here S3700040you can get a good lookat the older style sprag to the right of the picture. it has a thick lip of plastic on one side. is this a real critical thing to have to retro fit into these, i don’t feel it is unless there is a wear issue when you do your tear down and inspection. that would be the time to consider the retro fit to the 01 and newer design.



moving to the rear, the front planetarydrum and clutch used a lip seal type piston up to 1996 or so, then they switched to a molded style piston. the direct drum and intermediate clutch pack is standard with a 4 disc clutch, 34 element sprag, and spiro clip retaining the sprag. like the forward clutch, somewhere around 96 they went to a molded…..or what is also called bonded piston where the seal is bonded to the piston and cannot be serviced separately.

when we move back to the center support, although it looks just like one from a th400 it is not. it fits into the housing a lot more snug than a 400 center support. in 1999 there was some what of an overhaul to the rear planetary design to beef up the rear planetary gearset. to do this….like the front overrun clutch assembly, several components also changed. the rear of the center support was changed at the torrington bearing.

the sun gear shaft changed 3 times. 91-96, 97-98, and 99 on up. they also changed the sun gear shell in 1997…..ironically reducing lubricating oil flow to the rear planetary.S3700030 the part that absolutely baffles me is that they made the rear mainshaft solid in 1997. between 97 and 99 they changed the torrington bearing set up a few times but to be honest, here you can see the bearing exploded out of this 99 unit due to lack of lubrication. basically, like in a demo car, if this is in a plow truck where 1st/reverse is held for long periods of time, this thing has no direct lubricating oil and fails……this is what failed in this particular 1999 unit. it trashed the rear planetary. for shits and giggles though i stuck some th400 parts from an old bop tranny in it to re-assemble it cause these were so trashed…..and they almost fit perfect. all i have to say is someone bought a gem of a core off me!


the S3700031rear output shaft is about an inch shorter than that of a th400, but has over 2 inches more of spline area. here you can see a side by side photograph as a comparison.





down S3700046to the valve body the first thing to be aware of is that there are two different force motors. my index finger is pointing to the force motor, the other is a solenoid. 91-93 models were different. the 94 and newer ones are different….and the electrical/case connectors also changed in 93. there are two shift solenoids to the rear of the valve body that also need to be checked out. like the 4L60E there is also a switch manifold that needs to be checked .



oneS3700045 thing not to overlook is the the shift solenoid feed filter found beneath this plug to the rear of the valve body. you can also see the two shift valves in this picture. like the 4L60E, there are concerns for valve wear in the aluminum valve body. be aware of it. if you have a clutch pack failure or a driveability problem, you need to look into your valve body if there is no other obvious signs of damage. for me, in this tranny the damage was pretty damn obvious and the valve body looked great. i would still clean it out and change the force motor.



the frontS3700044 pump is a cast iron pump with a pump gear set up similar to a th400. the regulator is in a similar mannor as a th400 and can be accessed from the bottom through the oil pan. in the picture i am pointing to your TCC valves that are, unlike the 4L60e or 700R4, located in the pump as well. the valve to the right can be seen like the regulator valve through the oil pan area with the pan off….the other valve i am pointing to is a converter limit valve. during pump service these should be removed and cleaned to insure proper function. also i should note that the drive gear does not have teeth on it like a th400 pump. it is driven by two flats on the converter hub. so if you look down the pump with a flashlight and don’t see any teeth to drive the pump…..don’t panic!