Category Archives: Engine Tuning

2 Piston rings Vs. 3 Piston Rings

 
 THIS IS A VIEW OF A DISCUSSION I FOUND A LONG TIME AGO IN A GOOGLE SEARCH THAT I FOUND USEFUL IN UNDERSTANDING MORE ABOUT PISTON RING TENSION AND WHAT I HAD DONE WRONG IN SOME PREVIOUS ENGINE BUILDING ATTEMPTS. I DIDN’T WRITE IT HOPE YOU FIND IT USEFUL.
 
 
 
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.

BLOCKS

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.

LIFTER RETAINERS

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.
CRANKS

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.

RODS

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.

PISTONS

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.

 

BALANCE SHAFTS

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.
CYLINDER HEADS

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.
OIL PUMPS

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.

 

Rochester Carburetor Number Decoding

Did you ever wonder what in the hell the numbers on your carburetor meant? when it comes to Rochester carburetors, In this day and age it is damn near impossible to take a carburetor into your local part’s store and find a clerk that can even recognize a carburetor let alone try and find you a rebuild kit! so in a nutshell you need to know what your carb came from to begin with so you have an idea not only to determine what carburetor kit to get ,but what it may have been calibrated for. Remember when chosing a carb…yeah you can always drill/swap out some jets but with these older rochesters, the passages-air bleeds-main jet-cfm rating-etc are hard set for certain size engines.SO, unless you know for a fact where the carb came from always check the number to see what you are dealing with.

Example: # 7028219
DG 1938

On most Rochesters you can find these numbers covered in shit on the main body. on the q-jets it can be found near the rear corner face of the main body secondaries going up the side of it. on a 2G carb it is on the side of the float bowl. you can sometimes be lucky enough to get one with a tag on it still but that is somewhat rare…..and the numbers are usually covered in corrosion and shit and by mistake-you scrub the numbers off trying to read them. rebuilders may or may not tag the core after the build.

 

7028219

Prefix code. “70” will appear on all late ’60’s Rochester Carburetors.
76 and later will start with “170”
2 – Decade produced.
702 – 1960’s
703 – 1060’s with A.I.R.
704 – 1970-1975
1705 – 1976-1979
1708 – 1980’s

7028219

Year produced.
8 = 1968
If the number was 7045219 then
5 = 1975
7028219 Model
0 – Monojet (1 bbl) Federal standards
1 – Two jet (2 bbl) Federal standards
2 – Quadrajet (4 bbl) Federal standards
3 – Monojet (1 bbl) California standards
4 – Two jet (2 bbl) California standards
5 – Quadrajet (4 bbl) California standards
6 – VariJet (2 bbl) Fed
7028219 – Division.
0, 1, and 2 all indicate Chevrolet.
4 – Buick
5 – Olds
6,7 – Pontiac
7028219 – Transmission most cases
Even numbers – Automatic Transmission
Odd numbers – Manual Transmission
DG Production Code.
1938 Rochester produced carburetor Date Code
193 = 193 rd Day of the year
1938 8 = Year 1968
Other
A8 o MM Carter Produced carburetor Date Codes
A= Jan
B= Feb
C= March
etc….
A8 o MM 8 = year 1968
MM Production Code.
   
 

Adjustable Timing Curves and Heat Build Up

Heat build up in an engine is something that is a concern in several different motorsports. although different brand/make of engines/displacement/and fuel type play a major role in how to deal with heat, for arguement sake lets talk SBC with regular 89 octane pump gas for demo derby use, since that is the sport that seems to obsess about heat more than power.

 As a rule of thumb, i was always taught that less timing is less horsepower/more timing usually means more power to a point….which is usually 35 degrees at peak advance under heavy load or full throttle. so more timing-more fuel-more power- and obviously more heat as a result. remember from a previous blog i wrote about basic principles of performance: you don’t make horsepower without feeding the horse.

Now, so i don’t rehash something i already wrote about, here is a link to a previous blog describing advance curves and ignition. www.norespectracing.com/blog/?p=154 .so throwing real performance out the window i rethought a ignition set up.

a normal vacuum can advance will pull as much as 52 degrees of total advance at high vacuum like decelleration or high idle when base timing is set between 4-8 degrees on a stock engine. obviously at mid throttle this is reduced as it is usually plumbed into ported vacuum so it basically only pulls large amounts of advance at light load or cruising speed.

so what if we now use an adjustable vacuum can and plumb it right to the intake giving us full vacuum at everything but full throttle and cranking speed. we then use the can to crank the timing down to something more like 32-34 degrees. then set your base timing damn near stock at idle to just above zero (TDC) lets say 4 degrees, basically a low timing setting for cranking. lets leave the mechanical advance on the shelf for a moment and say it’s locked. Now, we have an optimum cranking timing setting for a hot engine, a quick response once it is started to a descent timing setting, and when you crack the throttle your timing goes into the toilet preventing any real power, which creates heat. so basically if you sandbag and feather the throttle you will build less heat than a stock distributor and have good response….longer overall run time. when you do open it up the 4.56 gear at the back of the car will make up for it. pair this with a loose bottom end and an absolute dog camshaft profile that will pull a high vacuum signal through a large part of the power band…… the thing may never overheat.

Now, if we include the mechanical advance it can be taylored to the rpm you want. a mechanical advance kit will give you the weights and cam to give you a broader range of rpm you can taylor your full throttle advance to. it also comes with different rate springs so the advance will be right where you want it at different rpm’s.

so lets say you use the springs and weights from your advance kit to conform your advance to come into full advance at 24 degree’s at 2000rpm. you obviously set it with the vacuum can unhooked running at above 2000 rpm with an adjustable light to verify the setting. you still have base timing set at 4 degrees remember. you then hook your vacuum can to intake vacuum and there you go.

you have good hot cranking-optimum low throttle timing for performance and heat build up- and and still have an option for full throttle timing adjustment. interesting theory right? well, to be honest i believe there might be something to it but i won’t do it. first off having a vacuum advance is just something else to go wrong and usually gets in the way of the distributor protector or at the very least makes it a pain in the ass. i still prefer putting the curve weights in and setting total timing with the mechanical advance changing around springs to come in at around your power band of your camshaft for full advance, then just chosing one total timing setting and leave it. BUT if you want to mess with multiple advance curves it’s something to think about.

Engine Build #3: Top end

S3700155Now what in the hell is this? well, after i got the bottom end of the block assembled and went through my dial-in to set my camshaft and timing, it was time to start on the heads. on the oldsmobile v-8 cylinder heads, both the center exhaust posts of each head feed the exhaust crossover to the intake. good for cold weather/ not good for performance. Chevy cylinder heads would also use either one or both center exhaust ports for the same purpose, but it was not as severe as on the olds heads.  there are numerous ways to block these off using block-crete, epoxy, and there is also some kind of a goofy zinc alloy you can use(which can melt). the way i do it is melt down some scrap aluminum and pour it through the exhaust post openning until it fills just below the exhaust port on the back side. i melt the aluminum in a blacksmith’s ladle and use the rosebud on the acetylene torch for heat.  now it isn’t contoured at all for peak flow and there is a reason for this. if you contour it into a nice bowl shape, the edges of your plug will erode and flake causeing it to end up just like you see it anyways. the best i have found in doing this is to create a wall/plug of aluminum at the back of the exhaust port pocket and leave it. these are factory heads mind you.

 in this day and age if you want serious performance :buy aftermarket cylinder heads and say screw it. more often than not it is cheaper than jacking around fixing up factory heads. but here again, i am just seeking to improve a pair of factory heads a bit not re-invent the wheel.  on chevy heads for derby engines i have done this with good results, but just welding a plug into the intake seems to do about as much good on a chevy small block.

 Now the next step in fixin up my heads was to go throughS3700157 the valves.  Since i am on a budget i elected to do what i call a polish valve job, which is actually a service technique i learned in trade school from an old fart diesel mechanic i had as an instructor. basically you take lapping compound you can get at any parts store and spin it with a power drill instead of that ridiculous stick with a suction cup. i don’t have all day to mess with that shit. as you can see in the photo i have a quick-chuck style power drill. you put 3 or 4 dots of valve gringing compound on the face of the valve, stick it in as so and spin it with the drill at low speed; lifting and applying light pressure in 2 second intervals. you want to go low speed and yo don not want it to bark loudly or screech as it grinds. this causes vibration which will ruin the cut. after you grind, clean em off and check your valve action. your valves should pop closed and sit flush to the valve pocket. if it doesn’t that you may have bad valves or need to have everything sent to the machine shop. also while you’re at it, check your valve guides for excessive side play. if they are real sloppy your valves can stick open.

what you are doing by lapping the valves to the valve seats of the head is mating the two surfaces together to improve the seal of the valves. it also works to clean the carbon and other odd deposits off the seats. it is a cheap ass way of fixing up your cylinder heads rather than completely ignoring em after you go through the bottom of the block. this IS NOT an alternative to a valve job from the machine shop. regrinding the valve seats and valve faces completely is the right way to do this. a 3 angle valve job is also an excellent idea but i don’t really see the benefit of it unless you are going to be doing other port work on your heads and try to flow some serious cfm’s.

once you get your valves in order, it’s time for springs. although you can shim your springs according to wear, i always replace valve springs when i am replacing the camshaft. the valve spring tension must match the cam lift requirements otherwise you will have problems. i also replace my keepers every time. your retainer are a toss up. i elected to keep my rotators since they were factory. on chevy heads i usually omit the rotators in favor of solid retainers on both intake and exhaust. once you install your springs, take a rubber mallot and tap the springs to make sure the keepers seat fully into the retainers. you would rather have em shoot across the garage instead of comming apart and dropping a valve into your new engine!

it’s time to bolt on your heads. don’t get into a hurry here.  this is where the chevy and the olds engines really went two different directions. on your SBC’s, it can be as simple as bolting em on and setting your valve lash. on the oldsmobile: the rocker arms are not adjustable. actually they are a piece a shit. the aftermarket adjustable stuff isn’t much better it is usually re-fucked ford parts. so before you torque make sure your valvetrain will not bind- especially with an aftermarket camshaft.

for a non adjustable valve train: assemble your heads to your engine block with hand tightened head bolts. do not torque. put in a couple of push rods and a few rocker arms. check to make sure your valve lash is going to be spot on. you may need different pushrods or even convert to an adjustable valve train to make your camshaft work. you want a bit over zero lash for a hydraulic camshaft to preload the lifter(check your factory spec). converting to an adjustable rocker arm set up may or may not require some major machine work depending on what kind of heads you have to convert to an adjustable set up. this is why you don’t torque your heads until you know for sure.

if it looks good then roll it to maximum lift on both the intake and exhaust valve to check for valvetrain bind. now there are numerous ways to check for your valve clearance to the pistons and/or rocker arm bind.  the most unique way i have seen is using play-doh on the piston faces while swapping in solid lifters for checking. you then roll the engine over slowly and disassembe to check your pattern of valve to piston clearance in the play doh. .

 on a hydraulic lifter set up, an aggressive camshaft can be binding the valvetrainS3700161 during assemble and never know it as the lifters are collapsing as your spin the engine on the stand.  it will bind after start up and snap the front of the camshaft once you build enough oil pressure to pump the lifters fully. this can be due to either the valves hitting the pistons from incorrect piston: cam timing combination, valve spring coil bind, or the rocker arms are not slotted far enough and they bind on the pivots. a simple check is to stick a big pair of channel locks on the rocker arm at max lift of the valve and pull the rocker arm down until you have play on the push rods. this also checks for coil bind on the valve springs. i would not be doing the channel lock method on a race engine with aluminum rocker arms. this is a simple check that works well for a cheap build like this.

NOW, once you have ensured you valvetrain is going to be alright. torque your head to specification and assemble your valvetrain. start at the center of the head and work your way out. i torque the heads on in 3 stages: like 20-45-85 ft/lbs, have a sip of beer in between stages to give the head gasket time to crush.

i like to use the mr gasket head gaskets for oldsmobile they seem to hold up better over the fel pro. it’s also cheaper. for SBC, i tend to shy away from the metal head gaskets- especially on derby engines. even when using the ultra-copper i have had gasket sealing issues with stamp steel head gaskets. i had better results with the cheapo summit head gaskets for SBC over the stamp steel fel pro gaskets. it didn’t matter if it was a light or heavy casting heads either.

there ain’t much left to do on the olds at this point , but you chevy guys(and anyone else with an adjustable valvetrain) have to set valve lash. on these is do what is called the companion cylinder method. you basically take your firing order and chop it in half. so 1-8-4-3-6-5-7-2, 1 would be in the same position as 6, 8 the same as 5, and so on and so forth. this is how most engines for automotive work.

look at your rocker arms. you want to set your valve lash at or close to TDC compression of that cylinder that you are on to ensure you are not part way on a lobe. so to start, you bar the engine over looking at the rocker arms on #6. when the exhaust is just about finished and the intake rocker starts to move: you are at or near TDC of number 1 cylinder and can set your valve lash on both intake and exhaust of #1.

once set, you go about a 1/4 turn on the crank and watch the rockers on #5 to do the same thing as # 6  having both rocker arms in motion: this will center #8 at TDC compression and you can set both of those valves for lash. you just work your way down the line and should make 2 complete revolutions on the crankshaft ending up back at TDC#1 compression when finished.

the main reason i like doing it like this is because with aftermarket camshafts can be ground all over the place. so it may seem like you are on the bottom of the lobe and you really aren’t- causing lost performance from incorrect lifter preload.

Engine Build#2:Camshaft Dial-In

S3700153

if you have never done this, or never even heard of this, it’s called camshaft dial-in. although not as many people do it as should, it is something i had to learn to do by force cause of this damn oldsmobile habit i have. unlike the aftermarket for chevy, olds performance products ore usually not right. i have only had two timing sets ever be spot on to there advertised markings. believe it or not the most consistent timing chains i have bought in recent years are the summit racing brand timing chains!

in a nutshell, your engine is a rotating assembly. your camshaft is designed to orchestrate your valve motion in relation to the rotational position of the crankshaft. by dialing in your camshaft, you are verifying that your camshaft and timing chain are going to fire off your valves at the right time and the proper lift to what you want. like i mentioned, there are numerous timing chains and camshafts out there, and they may or may not be made correctly. hell even my edelbrock cam was a bit off on the exhaust valve duration. a lot of your factory cams and bad replacements are ground retarded from the get go- and some of these multi position timing sets that actually sit 4 deg retarded at the 4 degree advanced markings!

Now, i could sit here and write out exactly how to do a cam dial in, but a quick google search will reveal some spot on articles on how to do it, as well as video’s you can watch on the web. you can buy complete kits to do this as well through summit or jegs. what i will do is point out a few things that i do whi;le going through the procedure.

there are a few ways of doing dial in, i use the intake centerline method with a dial indicator at the lifter. this eliminates all loss of lift through the valvetrain. yes, you can lose quite a bit of advertised lift through a poor valvetrain(like the olds). i use the large moroso degree wheel, a home-made pointer i made out of a bolt, and a piston stop i made from a piece of angle iron and a few bolts. i have a hydraulic lifter that has been welded solid with a plug so it does not collapse and throw off the measure of the dial indicator.

once i center my degree wheel to TDC #1, i position my dialS3700154 indicator directly on the lifter of either intake or exhaust # 1. you then zero the indicator and crank the engine around to .050″ lift at the indicator. look at your wheel and see how it corresponds with your cam card specs. if it is not spot on, note the degree’s of difference. this is the first sign of your cam timing being way off. i go through the process for both intake and exhaust lift. if all readings are off by about the same # of degree’s, adjust your timing chain…or in some extreme cases if it is off by 8 degree’s or more from the card on both intake and exhaust, shit can your timing chain.

as a rule of thumb, advancing your timing chain will usually help your bottom end power-retarding it pushed the power band up the rpm scale. for the most part, you should achieve correct cam timing with the timing set installed in standard position. if the cam is way retarded or advanced from the cam card while the timing set is installed straight up- call the manufacturer cause there is probably a reason for it, like valve clearance to the pistons for radical lift . do not plan on buying a cam and changing it at the timing chain from the get go. although it can be a neat way to save money- just save yourself a headache and buy the camshaft you want. use the timing set adjustments for fine tuning not overhauling the cam timing.

i quit buying used camshafts or anything without a timing card simply because you really don’t know what the hell you have. you can use this process to read an unknown cam or a camshaft you have ran for a few years to check for wear.

once i have my cam timing set, i wheel the engine to TDC#1 and remove the wheel. slide your dampener on(sometimes part way) and see where your ignition timing mark is located in relation to the true TDC location between your indicator and the groove on the dampener. you’re checking to see if the outer weight outer weight of the dampener has spun on the rubber and moved the mark. if this has happened, then you need to shit can your dampener. on the SBC chevy’s there were a few different balancers and timing covers so you can really mess up where you set your timing.

Engine Build #1: Bottom End

S3700147

Well, i must be an idiot as i have decided to build myself yet another olds engine after i swore the damn things off.  I pretty much have given up on the 455 olds based engines as after about 10,000$ and 6 blocks. i have come to the conclusion the block itself has an achilles heal. the olds V-8 blocks like you see here have the thrust bearing at the center of the block. i theory is that on the 455’s, when that 80lb crankshaft is under major load like going down the track at the drag strip, the crank bends like a fishing rod flexing the block. the center thrust bearing aids in absorbing the thrust from the front 4 cylinders- but the back 4 cylinders have nothing to help it. basically the #4 main flex’s and shits out the main bearings. some engines do it- some don’t all i can say is balancing and camshaft selection are key with 455 longevity. also- buy a girdle for the bottom of the block. Better yet go buy a chevy based Merlin block and forget about it!!

Anyways, when i finally sold my 462 drag engine a few months back, i got this mid 70’s olds engine in on trade. last friday i tore it down and i have to tell ya, it is one of the cleanest Blocks i have ever seen.S3700146 it literally had a stock bore with no piston ring ridge on the cylinders. the Crankshaft was also spotless with normal wear on the all the bearings. so i elected to re-ring it for future use on a street car i have planned to putz around town in. i am using a mid 70’s 350 block, plain jane crankshaft and the original rods and pistons. the identifying mark on olds blocks sits right on the top of the block behind the timing cover. in the picture here to the right above is the serial number you would look for for the good olds 350 blocks. after 1976, the bottom of the block on most all but the diesel engines had large windows in the supporting cast iron of the block for the main journals making for a very weak block to begin with. in my opinion the only block stronger that these 350 olds blocks are the DX designation 350 olds diesel blocks of the early 80’s(which can be converted to gas).

Now to do up an engine right, your block, crank, heads, rods & pistons need to be checked for wear and damage.  things like journal diameter and cylinder bore wear and taper. if you do not have the machinist’s tooling to do it, find a GOOD machine shop(which can be hard to do) . if you are building a high dollar power plant, you should definitely have the block, crank, and heads magna-fluxed for cracks that cannot be seen by the naked eye. pretty much in my book any engine that will see over 350hp/ 5000rpm OR serious amounts of abuse should be checked. things like lifter valley crack can become major deals the more you push an engine to the limit.

 NOW, does this mean you cannot build an engine without a trip to the machine shop- of course not. in my case i started with a great core and have a 500$ budget to get the thing running, and it will not see serious abuse. if the machine shop is out of the question for whatever the reason….usually cost….here’s a list of things not to forget while tearing down, inspecting, and re-assembling you short block :

– i always check all 8 bores with a bore gauge for size and taper due to wear. visually check for pitting and wear to the top of the cylinder. slight ridge-ring is not a definite sign of needing machine work. a ridge reamer can take care of a lot of it. as a personal rule if it is over .010″ of wear you really ought to consider boring it out….however if you are building a loose derby motor, ring seal is not quite as critical so .010″-.015″ is not all bad. in that case the engine i built to run extremely hot and will actually run better as it runs hotter due to the tolerances tightening up. it’s a fine line- too much and you will have piston slap.

-always check the journals on the crankshaft with a micrometer and visibly look for hard wear and damage. you are checking for undersize and taper. if the bearings look bad- chances are the crank is screwed. even if it looks good, if your engine was making noise CHECK IT!  you never know when someone else has been into an engine haf-assed the assy with the wrong size bearings at some point in the past and it bites you in the ass(it happened to me years ago). if your sizes are not to factory spec, look over the crank for any markings on the ends. machine shops usually stamp an undersize on one end of the crank on the counterweight.

-check your pistons and the old rings. look for stuck rings. clean any and all carbon from the ring grooves with a piston ring groove cleaner so your new rings will not jam between the cylinder walls. make sure piston pins are free. check the rods for blue marks….some discoloration of the rods is fairly normal, blue indicates heat damage and it must be replaced.

-if you had spun main bearings or severe bearing damage, the alignment bore of the crankshaft in the block could be compromised and you will need to make a trip to the machine shop, or shit can the block if you have a pile of cores….LOL!

-if you are not replacing the camshaft take a pair of calipers and check EVERY lobe for wear. 90% of the time you will find one that is not up to snuff. always replace the timing chain. always dial in your camshaft. if you do not know how to do this- learn how to. over half of the timing chains on the market are not accurate, and camshafts may or may not be ground retarded in the timing from the get go. you can lose incredible amounts of performance because of this! on some applications it can cost you an engine at start up cause the valves hit the pistons!!

-stick your new piston rings into at least one of your cylinders with a piston to center them and check your piston ring end gap. excessive gap for a derby engine is not hyper critical. you just don’t want it to bind.

-if you are going to run it over 5000 rpm on a regular basis, having your rotating assy balanced is a good idea. if you are changing hard parts like rods & pistons and they are not factory replacement, you should definitely have everything re-balanced. new and oversize pistons are suppose to come from the manufacture already weighted to a factory piston weigh, but the quality control on some of these parts can be a little left to be desired.

-when you are installing engine bearings, do not touch the bearings with your fingers if you can help it. the acid from your fingers can put marks on the bearings. i put a glob of lubri-plate engine assy lube in the middle of the bearing and put it together. S3700149you don’t have to lick the bearings and fondle em like your having sex, you just need to throw some on there so it isn’t dry! i also use two pieces of 3/8″ fuel line with dowel rods stuck inside to not only guide the rod ends onto the crankshaft, but it also holds the bearings into the rod ends so they don’t fall out onto the floors while you are trying to install the pistons into the block leaving both hands free to run the piston ring compressor. always use red loctite on the connecting rod nuts.