383 chevy with double hump heads

I need some advice on this, my 355 short block recently wiped out the bearings. My friend has a 383 short block with flat top pistons,I want to use the top end off my 355, its 461 casting heads, 64cc, 202 160 valves, cam is a solid lifter 256 264 at 50, 504 504 lift, intake is a victor jr, 750 holley vac secondary, how much horsepower will this make and how much compression will this be, also its a street strip car so mixing race fuel is ok. Thanks john


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You're going to be up there on the compression ratio, and Hi-Test fuel will be a requirement. Be sure and get your "quench" set right from the start, somewhere in the area of .035 to .045.

We figured the compression will be close to 10.9, i plan on running 110 octane race gas, what kind of horespower could i be looking at with combo, is the double hump heads going to hold me back alot? I was running 12.30s with the 355 in my 3800 pound 55 chevy wagon with 4,000 stall and 4.86 gears. 28 x 10.5 slicks it would 60ft 1.65 and cross the finish line at 6300rpm, the stroker has a scat totating assembly, will it be safe to 6500. Thanks for your help.

Static compression ratio will be 11.1:1 with flat-tops, 7cc's of valve relief and 64cc heads. Assuming this is a cast crank, the Scat cast cranks are cast STEEL, not cast iron, so I wouldn't hesitate to wind the motor to 6500 if it's kept out of detonation and is properly balanced.

Its a Scat 9000 crank shaft, and the rods are 5.7 summit stage one rods good for 525hp. Its been balanced but do you think those rods are the week link? He had aluminum afr heads on it that were 72cc and it was in a chevy two street car he took the heads off and used them on something else. Is 475hp realistic with those hump heads.

Did I miss what valves you have in your double humps? I can not remember if the 461s came with the larger intake valve as well. I think 475 would be realistic, but you could possibly do a bit of porting and approach 500. All this is a WAG based on what my 383 had when it had a milder cam and big valved 882 heads.

Trees