Was there a doughnut between the exhaust manifold and the exhaust pipe originally. When I took it apart there was what could of been remnants of one....but I am not sure. Hoping someone might know..I can't find anything on the web.

Thanks.

I can't say that I know for certain, but according to my '67 - '75 Pontiac Parts Book (on CD) there is a sort of answer. There is some inclusion of earlier stuff back to 1956 on the CD. According to Group 3.611, there was a doughnut "Gasket-Ring, Exhaust Pipe to Manifold" used through 1962 on regular production Big Pontiac V8s (through 1964 on Trophy 425-A & 421 H.O.). There is nothing listed after that before 1970, and those later ones are all Chevy-powered with 250 or 307 engines. I guess that means that no doughnut was used on stock manifold equipped 389 Catalinas in '66. There are repros of some of the better exhaust manifolds; getting in touch with a supplier could help lend credibility to my response or blow it away completely. Hey, what do you want for nothing?:)

Besides, what was sold up here in Canada at that time was almost always pure Chevrolet underneath (250 -427, generally 283 -powered).

Cam,

Thanks for taking the time to help.

Jon

According to my parts computer its not required for either engine available that year. Doesn't mean much that the parts computer says that, but just thought i'd mention it.

Thanks.

on all pontiac exhaust manifolds from 1964 to present, there is no gasket or donut between the head pipe to the manifold. now when they changed to the removable heat riser like on the chevy, then sometimes a gasket was used on the flat side of the heat riser. All pontiac head pipes are flared to fit against the manifold.