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I ran those pistons in my 455 with E heads for many years with a 200hp shot of nitrous oxide. They held up great with hundreds of runs on them. The beauty of them is you can run on regular gas in the street. My 1970 442 ran 11.50's with them at 4075# with 3.42 gears! 1994 Olds day at Etown finals. My Olds motor coach
I'm looking to build a torquey low compression 455 that'll pull a 2.56 rear for long distance cruising on 87 octane gas. It's going in a '66 442 4 speed and will probably use some 'B' heads, Performer and HEI. Already got a standard '70 block and 4 speed crank.
Horsepower and Torque are directly proportional to compression. I eventually shaved the heads and used a thinner head gasket from Rocket Racing (.028") to boost compression to about 9:1. You may also try an original style steel shim gasket (.017"). It will still run on regular gas. Try a cam with intake duration around 214@.050"
i also have a 455 .030 over with 2390 low comp pistons. You mention shaving heads and cam change. How’s that working for you? Happy with results?? I am so ready to pull engine and replace pistons but that’s a lot of work. Please respond. Thanks
i’m happy, but I also had my E heads ported and added a Holley Street Dominator manifold. The car picked up about 0.4 seconds in the 1/4 mile. The real beauty of the low compression is you can use any grade of gas in it without pinging. I also hit mine with a 200 hp shot of nitrous on hundreds of passes with no detonation using 93 octane. My experience with iron heads and 9.5+ compression all ping in hot weather with 93. With aluminum heads you will not have problems with pinging at 10:1 compression.
i also have a 455 .030 over with 2390 low comp pistons. You mention shaving heads and cam change. How’s that working for you? Happy with results?? I am so ready to pull engine and replace pistons but that’s a lot of work. Please respond. Thanks
This the cam I currently have in my 455 with 2390 .030 pistons. Seems duration doesn’t match what you recommend. Negleble difference or part of my power problem?? How much did you shave the heads?? Summits compression calculator puts me at 8:1 currently with C heads. What do you recommend??
Your cam is fine and close to the max duration for low compression. Did you degree it when you installed it? My experience has found that half of all the cams I checked were retarded which seriously affects power. My heads were milled down to 74cc volume, plus a thinner gasket. Felpros are .038” thick, I used .028” from Rocket Racing because my block was O ringed for nitrous. If you can find steel shim gaskets even better, they are .017” thick. If you really want to go, I recommend installing a 100-200hp nos plate system with a msd timing retarder. I had my 70 442 (4075# ) doing 11.50’s with 3.42 gears! If you want to talk about it, we can trade cell #’s. Bob
November 1st, 2020, 06:57 AM
