Olds Engine 77-90

oct08055The picture to the left is a shining example of the 77-90 engine blocks for v-8 oldsmobile. this one here is a 403 olds engine that grenaded. in 1977 the block and cylinder head castings were re-designed AND re-issued across several gm factory lines. these engines were the 260, 307,350, 403, and the 350 diesel.similar to chevy small blocks, on the outside they were all pretty much identical. the base design of the block and heads remained as far as accesory’s, head and block dimensions as far as looks and how it bolts together, covers, oil pump, etc. with the exception of the diesel, pretty much older SBO heads and blocks will interchange most parts with the newer ones so you can mix and match.  the thing is that  all of these engines had in common is the amount of iron they put in em was reduced when it should have actually been increased- creating an even weaker platform. even though these engines were oldsmobile they to me are a completely different engine from the older generations. most of the casting designations are a large number followed by a letter(as i stated in another blog). i am going to address each of these engines separately and in a different manner as i was around these as a kid/teenager. as they are all an abortion unto themselves i will adress each of these individually..

When i was a kid, my dad got a used 82 cutlass station wagon with a 260 olds engine. it ran right for about a week and then for the next 3 years or so that he owned it, it was a nightmare. as a kid, it was the car that made me realize the power of a good mechanic- and the horror of being bullshitted by a bad mechanic. that car was an awesome solid car but was plagued with problems. we nicknamed it the copper bomb cause we always figured it would explode one day. it was a terribly under powered piece a shit, equipped with the half-assed q-jet carb and computer controlled HEI, it would simple never run right. to be honest you couldn’t see the engine as there were so many vacuum lines on the thing . my dad more than once threatened to reach under the hood and rip it all out like spaghetti! because it ran terrible from a poorly engineered engine management system, the engine carboned and loaded the engine full of sludge, plugged the intake and the oil return ports in the heads, bent push rods, rocker arms, overheated more than once. finally one day the tranny locked up at a stoplight and she went down the road. hind site 20/20, if you could have ripped the carb and dist off an older mid 70’s 350 ,it would have probably given the engine new life. but it those days it was the dawn of emissions/fuel management systems and unlike today, most mechanics outside of a dealership didn’t have a clue how they worked or how to work on em so they would throw parts at em and bullshit the customer over-and over-and over.  i hate to know how many times the old man got screwed on that car by an ill equipped mechanic. the engine simply never had enough power to ever put stress on the block. so in that reguard the lack of iron didn’t matter.

next would be the 307. now these believe it or not were a good engine. i, along with many friends, but nearly 200,000 miles on these engines without burning oil. now they had the same horseshit fuel management systems, but where the 260 was literally smothered by it the 307 survived, AND did not have enough power to stress the block. these were found in a lot of full size buicks and oldsmobiles from 1980-87, whereas chevy’s and pontiac’s got the 305 chevy. the 307 was not over powerful, but simply got the job done. the early 80’s 307’s were a bit sturdier in my books. from what i can gather sometime around 1984 they incorporated a swirl type combustion chamber for the cylinder heads and they really didn’t have the same longevity of the older 307’s. a 307 has windowed mains so if you want to put any kind of performance parts into a 307 block a girdle is the best place to start. i do believe that a 307 has a stock class speed record in nhra somewhere in the 12’s but i am not sure. don’t really give a shit to be honest.

next is the 350 gas engines from 77-newer. basically the same engine as the older 350’s but the main webbing was cast so thin there were windows in the casting above the crank: leaving only 3 small pieces of cast to hold the crank in on each journal. i am not sure what moron had the idea to do this, but in a stock application it would live because they put it in cars with a 260 rear axle gear so it was damn near impossible to stress the engine. of course like the 307, if you want to build it-start with a girdle. the cylinder heads were also a thinner smog casting different from the earlier ones. easily identified with an “A” after the number designation on the lower left corner of the head. i personally shit can these engines when i find em as the older 350 olds engines can still be had reasonable and it make perfect sense to go that route.

then there is the 403. my 77 olds 98 was originally equipped with a 403. these things were in full size cars from 77-79 primarily with a 2.63 rear axle gear and a th400. they were basically a 350 block with an ungodly huge bore and of course the windowed main webbing on the block. they also put these in the trans am’s in the late 70’s using a conversion bracket and a chevy motor mount. it’s kind of funny if you ordered a trans am with an automatic you got an olds 403; if you wanted a 4 speed you got a 400 pontiac engine. it’s because the bottom of the block was weak from the get go and GM knew it if you ask me. as with the car i had, usually even when driven by an old lady these things went to shit and were scrapped many years ago. BUT, the wild thing about the 403 is it retained the largest standard cylinder bore produced  from the factory at 4.35, yet retained the 350 stroke crank. so the potential for big horsepower is there, and many people have tempted fate. some did it successfully, and others like in the picture at the top weren’t so fortunate. if you really want to see and know about some wild 403 olds stuff seek out my friend Jim at www.jsmachineoldsmobile.com . there are others in the country that get into hardcore olds engines, but i think he is pretty straight up and seems to know his shit if you ask me.

and last but not least is the dreaded 350 oldsmobile diesel engines.after the fuel crisis of the 70’s, there was a call for mileage and the 350 diesel came about…touting 30mpg it was a sales pitch for the cars gm produced in the late 70’s. it was a half assed engineering feat if you ask me. it was basically a gas engine with a steel crank, flat cylinder heads, and a roosa-master injection pump atop the front to inject fuel. these engines still had a plug at the back like a dummy distributor to drive the oil pump. 

now as with anything produced that could possibly fail, of course my old man owned one of these engines also in an early 80’s station wagon. actually i had a few relatives that owned these as a kid. they indeed would get 30mpg in town, and were some noisy bastards that didn’t like cold weather. these things had weak blocks and were known for popping head bolts and cracking the block- after all it was a gas block not a diesel. by 1981 gm figured it out and re-cast the block heavier to solve the problem, but it was too late they had such a horseshit reputation that they were discontinued soon after.

 the later diesel blocks were given a “DX” designation. these blocks were beefy and could have the boss for the injection pump machined off, older heads and intake installed, and you could enjoy a 9:1 compression gas engine with beefy block and steel crank. some guys will overbore the hell out of these blocks and squeeze a 400 or 425 crankshaft into it for racing engines. not real cost effective though.

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