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I am looking to get a little more power out of my 1976 Oldsmobile 350. It's a low milage engine about 30k on it. Bone stock four barrel. I have read going to 7a heads and a w31 cam will wake it up a lot. It has true 2.5" duel exhaust. 2500 stall, 200r4 transmission stage 2 from twisted torq. Ford 8.8 with 3.55 gears. It's in a 1963 Pontiac LeMans. Car weights about 2800 pounds.
The 73-76 engine had smaller piston dishes (~14cc) than the 71-72 engines (23cc), but used larger combustion chamber heads (~80cc) than the earlier engines (~68cc) to keep the same advertised 8.5:1 compression ratio. So yes, using earlier heads (5, 6, 7, or 7a - they're all equivalent) would bump the compression some. I don't know that it would bump it into the range where W-31 camshaft would work, though, as I suspect it would still be under 9:1.
Trying to figure out a way to bump up the HP without dumping a ton into the engine. Found 7a heads for $200. My current #8 heads are in great shape, could you shave those down to up the compression? 9.5:1 would be ideal.
Not worried about the transmission, rear differential or driveshaft was all built to handle 550+ HP. The transmission is a BOP bolt pattern. My plan one day was to build a 400 Pontiac or maybe LS swap it. I wanted a little more cheap power for the time being. I came across the 7a heads for $200 and reading other forms some people claim swapping the heads and cam would bring the engine to about 300/325 HP from the 190hp.
A 76 350 minus pellet cat and true dual exhaust is 200 net hp. Possibly 220 with full length headers. That's a 13 second car in a perfect track scenario... nowhere near 300 hp, but she must move nicely. So light !
No I haven't. It moves pretty well. It is more built for handling than the strip. Four link suspension. QA1 coil overs. Once I get some more life out of the current engine I'll run it on the strip to see. I am pretty confident with the 7a heads and a better cam it will be in the 300 HP range.
No I haven't. It moves pretty well. It is more built for handling than the strip. Four link suspension. QA1 coil overs. Once I get some more life out of the current engine I'll run it on the strip to see. I am pretty confident with the 7a heads and a better cam it will be in the 300 HP range.
Nice looking car. I think that body style came with a 326 C.I, Pontiac with a fragile trans axle. I think with high compression pistons and W-31 cam you might be almost a quick as an early (1964) GTO.
Yes that was a 326(336) the engine was different in 1963 it was a 1950s 389 block with sleeves. 2" Longer and more displacement but couldn't be advertised bigger than the Corvette. This one had the two speed transaxle. If it would have been a 3 or 4 speed manual I probably would have left it. I never had an issue with the transaxle or the torque tube. The engine was more problematic than anything. That is how it ended up with the Oldsmobile 350. I mated that to the original torque tube. Ran it like that for 5/6 years. Than I wanted more gears.
Yes that was a 326(336) the engine was different in 1963 it was a 1950s 389 block with sleeves.
Interesting. I never knew that.
Originally Posted by BOP63
2" Longer and more displacement but couldn't be advertised bigger than the Corvette.
I see Corvette has been playing this game for a very long time ....
Originally Posted by BOP63
This one had the two speed transaxle. If it would have been a 3 or 4 speed manual I probably would have left it.
I believe you, much quicker and nimble car, and the stock 352 lb ft of torque makes the drive fun.
Originally Posted by BOP63
I never had an issue with the transaxle or the torque tube. The engine was more problematic than anything. That is how it ended up with the Oldsmobile 350. I mated that to the original torque tube. Ran it like that for 5/6 years. Than I wanted more gears.
I see, you went from problematic to problem free. Great choice obviously.
You follow a plan of subtle but ideal modifications. That sets the table for the next upward move. Now I see why you will be good for the time being with a 50 hp boost.
Cutting to the chase and going all out bigger and built not necessary for now. Having an engine pro built to 600 hp may be more cost effective in the long run. But once your maxed out the pleasure that comes from chasing more starts to fade.
I wanted a little more cheap power for the time being.
Originally Posted by cutlassefi
Change to at least a 3.42 rear, lose the 600 and regular Performer and replace them with a 750 and RPM. Get a set of 5, 6, or 7 heads and a mild cam and you'll reach your goals.
If your not familiar, cutlassefi is a resident engine builder who frequents this site with a proven track record. The original poster of the thread wanted his original 1976 350 powered 442 to run a 14 flat. cutlassefi gave him the formula to do it. Unfortunately the OP may have lost interest after he track tested her before the further modifications. She ran 16.5 @ 85 MPH essentially stock but with long tube headers and true dual exhaust. He was very disappointed, his last thread from 10 years ago was dedicated to the disappointment. He hasn't posted since. And although fellow members like BangScreech4-4-2 pointed out that she actually ran great, which she did, he disappeared...
The thing is, bone stock new the car ran 18 seconds at 77 mph. 1976 442s were terribly inefficient for performance, weighing 4000 lbs without driver was a big part of it. His basic mods picked up 50 hp in performance. Hot Rods 76 350 442 showed 150 flywheel hp from its performance. While the OP showed 200 flywheel hp. With his then 40 year old 95,000 mile original engine version. The reality was the car ran exceptionally well.
BOP63 your ride is about halfway home when considering the recommended mods. Better heads and cam should do the trick. Just wish you could track test it before and after...
I added #6 heads milled to 55cc on a completey stock 1976 Olds 350 bottom end. What you need, if you want more that 9.5 to 1 compression with regular replacement head gaskets. I had about 9.6 to 1, pistons will be at least .025" below deck and a .042" Felpro compressed head gaskets. It ran 9.4 in the 1/8 in a 3750 pound plus 225 pound me in a 88 Cutlass. Every run picked up, 1/2 turn richer, each of the 3 runs. Pretty sure I could have hit low 9's pretty easy that day. Only had the 204/214 cam, Sanderson shorties with 2.5" X pipe dual exhaust, 2350 stall, 2004R and 3.42 open rear with 26×8.50-15 Mickey Thompson ET Street bias ply slicks. It would not have been far off 300 HP. Add more duration, many choices with more vacuum and better manners than a W31 cam.
Last edited by olds 307 and 403; Nov 4, 2025 at 08:33 PM.
Thank you for the information. This car should get up and move pretty quick when it's done. I found some 7a heads. I am going to port match the intake. Run center dump headers. Comp full roller set up. Get away from the flat tablet game
