Originally Posted by 075turbo
I have a SBC 350 with 882 heads which have 1.38" "Square" exhaust ports. The headers that came with the car are 1.30" x 1.65". In looking through a Summit catalog, I'm having a hard time determining what gasket to select because none of the listed sizes seem to match what I have. Earl's makes one that is a 1.36" square port for a 350 but the other companies start out at a 1.50" square for this motor.
For the intake, the heads are 2" x 1 1/8" and the Performer RPM manifold is the same size so that is pretty easy. My question is that some say that the crossovers are blocked and others say that there is no exhaust crossover opening or blocking shields. What is the difference and which would I need?
To start with you have a miss match between the header size and the head port. You need to determine how these match up. You do not want a situation where the header flange hangs inside the port ID. However, it the header flange is larger than the port, this is OK, not ideal but better than when the overhang is the reverse. The speed shops sell adapters that can be used to adjust any miss-match.
The Performer RPM has provisions for exhaust heat under the intake as do your 882 heads. If you live in a cold damp climate, this is a feature you will want on the street. Otherwise blocked or absent crossover opening in the gasket is fine.