Thread: Chevy 355/305 heads

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I got a car back that I had built for my son 9 years ago. A 1978 Olds Omega. It doesn't run now-used to-really well. 14:30's at Bandimere Speedway which is at 5500 ft. Chevy 355 with 305 heads (62cc-1.84 intake) reworked, pinned, match ported to an Edlebrock Performer manifold, 600 Edelbrock carb, exhaust cutouts, 4;11 rear end, 2500 stall converter, more details...Isky hyd cam #201292 w/505" lift. My son had put a 525" lift cam and 750 Holley carb in it before it quit running, I calculated at the time that a 505" was the biggest that would work. He proved me wrong and ran it with the bigger cam for about a year.
I am not a mechanic but I got lucky with this combination. For the $ I put into it, I got more out of it.
My question; How to determine the best combo: 505 or 525?

Originally Posted by marvinphoto

I got a car back that I had built for my son 9 years ago. A 1978 Olds Omega. It doesn't run now-used to-really well. 14:30's at Bandimere Speedway which is at 5500 ft. Chevy 355 with 305 heads (62cc-1.84 intake) reworked, pinned, match ported to an Edlebrock Performer manifold, 600 Edelbrock carb, exhaust cutouts, 4;11 rear end, 2500 stall converter, more details...Isky hyd cam #201292 w/505" lift. My son had put a 525" lift cam and 750 Holley carb in it before it quit running, I calculated at the time that a 505" was the biggest that would work. He proved me wrong and ran it with the bigger cam for about a year.
I am not a mechanic but I got lucky with this combination. For the $ I put into it, I got more out of it.
My question; How to determine the best combo: 505 or 525?

I know the engine guru's will probably chime in but I believe your spinning your wheels with the 305 heads. Unless they were really reworked and done properly. They have small chambers, but also small valves and small runners. And what are you running for pistons? Stock, dished, or flat tops's. If you want to go faster, best money will be in a decent set of heads. But I'm no genius. It's just my humble opinion.

That's exactly what I was told by all except for a guy that used to be on a top fuel (reworking 426 hemi's) back in the day. He said that it will either run really well or not-it was a gamble. The heads were reworked professionally (Heads by Paul-Denver) What happens is that it supercharges the mixture due to the smaller heads. It ran really well despite the 305 heads. Flat top pistons.

It will run even better if it breathes more efficiently.