Hey Mike,

I hope I understand you correctly.

The insulator does not block any coolant passages. In the pictures below I outlined where the water jacket is. Not saying that it's impossible but the water jacket in the intake would have to corrode through about 1/4 - 3/8 of aluminum before it reached the runner. I think the first thing to corrode would be either the freeze plug or one of the nipples where the hoses attach.

Hey Mike,

I hope I understand you correctly.

The insulator does not block any coolant passages.

Well, as always I could be completely wrong. However, I recall that on my '72 there are actually coolant passages through the insulator to help cool the carbs. I'm going to hot link a picture from ZTherapy (while I still can) that shows the differences between model years. The pictures you posted clearly don't show the passages I'm thinking of and I didn't realize that earlier cars did not have this feature.

Well Mike I stand corrected. Sorry for the bad info. I had no idea. I guess I learned something new today. I wonder if that is only on the 72's?

Thanks for correcting me .

Bruce you around?