Originally Posted by truckboy61
I'm in the process of changing out gaskets on heads and intake and noticed that the gasket on the intake was blocking a port ? It's located in the center of ports on both heads and intake and a friend said they believed it was called a " heat transfer" and blocking it was OK ? I also noticed the gaskets were embossed with the same pattern as if it was possible to cut it out? Any ideas of this port and if it's OK to block ?
What you were told is correct for the most part. The heat crossover heats the underside of the intake to aid in the atomization of the air/fuel mixture and keep it in suspension so it doesn't drop out and puddle, which causes drivability problems, slower warm up and more emissions.
That said, there are cases where the gaskets are used blocked on one or both sides, in performance applications, mostly.
If the intake is on a SBC for instance, the intake is getting hot engine-temp oil splashed onto it from the lifter valley, and this will eventually heat the intake up quite a bit. This is the heat that "air gap"-type intakes try to eliminate by their design.
Pontiac and others have "valley pans" that cover this area, and are in effect "air gap" intakes already, although these engines have a separate heat x-over to aid in carb heat.
Just what engine are you working on?