Heat riser passages...

[COBALT]

I'm starting to question the whole heat riser passage thing in the intake manifold. The replacement manifold has two open passages. I got a feeling that the one still on the engine has two open passages as well. I have no idea how stock 350 heads are set up. I think I read somewhere that 350's 79 and up are blocked on one side. Mine's a 1980 block.

The gaskets I got are open on both sides, but I started thinking about leaks and how much i HATE them, so I got a set of pro seal intake gaskets from Mr. Gasket. Well, the heat riser passages on both sides are blocked. What the hell? What's the significance of the heat riser passage and if I block them or leave them open what would the effects be?

Remember this is a 350 with stock heads sporting a 327 manifold and a 2bbl carb.