Hot Rod Forum banner

How is my build?

915 views 10 replies 6 participants last post by  granprix76 
#1 ·
Well this weekend the car should be started for the first time. Here is what I have.

Pontiac 455 bored 60 over
Balanced rotating assembly
Edelbrock Performer RPM, Aluminum 72cc
HS RR 1.65
Torker II intake
Comp XE Cam 240/256 507/510
Quick Fuel 850DP carb
MSD 6AL
MSD Dist
373 gears
TH400
3' exhaust
 
#3 ·
Sounds like a good setup but before you fire it make sure that you cna get some racing fuel as your compresion ratio is going to be extremely high with those heads. Right at 11.5-11.8-1. The gears may be a little steep but should be a good performer. This is a very heavy car and is going to take alot of torque to get it moving. Let us know how it turns out.
 
#6 ·
With 72cc heads if flattops are used the compression will be in the range I specified. Even if the pistons are dished the compression will still be above 10:1 which is too high for pump gas in a Pontiac. 9.5:1 max for a Pontiac pump gas street engine. The 3.73 gear is a little steep for a 455 as 3.55's are a better gear and keep the 455 in the lower rpm range it was orginally designed for, even in such a heavy car as a GP, maximum rpm should be kept at 5200 unless forged or aftermarket rods are used. Then maximum rpm would still be limited to 5800 as the 455 has increased rotating mass due to the 3.25 main size. There are a lot more variables when building Pontiac engines that have to be taken into consideration before building can begin, much unlike a SBC. The 455 Pontiac is a low rpm torque engine and with the large main size is very limited on rpm. 85cc Edelbrocks would have been a better choice and would have put the compression at 9.5:1 and still make for an extremely strong engine. Also the 455 will make excellent power with a slightly smaller cam that would operate in a lower rpm range. If this is to be a strictly street driven engine you won't be happy with it as I referred before you will need racing fuel for this engine.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top