intake manifold question

[swtman]

What is the purpose of an open center manifold? I have a 305 approx a '78-79 in which I just put in a new intake gasket and not sure if maybe I should have put in a restrictor in one side. What is this restrictor supposed to do? I have a newer 4 barrel manifold on it. Should I have put the restrictor in? Any help would be appreciated!

[prostreetC-10]

I believe that the opening is usually for a carb with a divorced choke. Choke has a coil on the manifold and the heat operates the choke. The restrictor keep the heat from getting into the manifold. Problem is that many times, when you put the restrictor in, over time they burn out anyway.....it will be open one way or the other. This is my educated guess. Anyone else???

[GruntMoanCough]

Blocking these off will give some free horsepower by keeping the intake cooler but, for street use this will increase warm up time.

[swtman]

So it's ok that they are both open? It won't cause the manifold to over heat or anything??

[GruntMoanCough]

I don't think it will cause any problems.

[mclairmo]

It's ok that they are both open and might be best considering your location. This is how the factory did it to help with cold start warm ups. Allows warm exhaust gases to run under the carb to increase fuel atomization when cold. In cold climates, you need this. However, in warm climates, many hot rodders block this to help keep the intake charge cooler and denser for more power.

[swtman]

thanks for all the replies guys!!