I believe the ports you are talking about are the exhaust passover ports. They are there to provide heat to the cast iron manifold to help keep the gas atomized and to help prevent carburetor icing. You don't have to clean them out in fact most people plug them up, especially when switching to an aluminum manifold. You may be able to find gaskets that are not cut out for the ports. It's been a while since I messed around with a small block but I think they are still available that way.

 

I'm sorry, I mean't exhaust "crossover" ports.

 

Thanks 69FE, thats a relief to know I can leave the heads in place!....On the 2bbl to 4bbl carb conversion, obviously the spacer is eliminated also. My question is do I have to include a spacer in the new setup (described above) ? Is the spacer's purpose to reduce heat exposure to the carb off the block(manifold)? And is the height of the spacer (1/2" or 1') needed only subject to everyone's particular hood clearance requirements or is there more to it? Thanks AGAIN, John