Carb insulator gasket
Hello. I have a 1969 El Camino with a 350 eng., stock manifold and an Edlebrock Quadrajet spread bore. I took it to a shop awhile back and they discovered that it had a blown gasket under the carb. They fixed it. I took it out on the freeway a few days ago and got on it to get rid of some carbon. After that it started running lousy. I listened around and heard a vacuum leak around the base of the carb. I took the carb off and it looks like the gasket itself may have been leaking. My question is that it has a 4 hole gasket with a closed center on the bottom. Above that it has a 4 hole metal gasket with a closed center and above that it has a 1/4" thick open center heat insulator. The center of the bottom gasket was almost entirely burned away and the metal gasket center was partly burned away. On the front of the intake under the carb there is a channel that runs left to right and I see a trail of carbon from this channel back under the center of the gaskets to where they are burned through. I am thinking of replacing the 1/4" thick heat insulator gasket with a closed center 1/4" heat insulator gasket so that the centers of the thin gaskets would be sandwiched between the carb and the intake. Does this sound right? Does anyone know what this channel is on the intake? Please see the attached pictures. Thanks for any info you give give.