[fastd]

while you are in there, if you have the clearance, i think adding a heat shield might really help deflect some of that nasty heat radiation (despite the fact that I said above that it didn't do much by itself) and allow the phenolic to stop the conductive heat. The Holley heat shield comes with a squishy gasket; and the CoolCarb looks like it comes with a with one that some kind of composite filled material (but it's layered between aluminum for rigidity).

If you don't have the clearance and have the room to only put on thing on I would go with the phenolic spacer...however, it is usually not that kind of choice. If you have only 1/2" of room, personally I would go with a 1/4" phenolic and a heat shield rather than a 1/2" phenolic. I had limited clearance on that pontiac i mentioned and went with a 1/4" and heat shield and it fixed it (again, I haven't tried it in the heat of the summer but I was having hot/hard start issues in the dead of winter - at 35-45 degrees). On my Cobra I have a 1/2" phenolic (with a heat shield) and I don't know that it makes much of a difference. Ideally, heat shield with 1/2" phenolic is obviously the best.

I actually think that the best set up would be 1/4" phenolic sitting on top of the manifold, then the heat shield, then another 1/4 or 1/2" phenolic on top of that.