I am installing my Gibson headers and the instructions say to use the "stock O-Ring gaskets" between the headers' collector pipe flange and the Y-Pipe flange. I did not see any type of gasket in this location.

Did you have a gasket between your stock exhaust manifold and the Y-Pipe? If not did you just bolt the two flanges together? Any leaks at this joint?

I am installing my Gibson headers and the instructions say to use the "stock O-Ring gaskets" between the headers' collector pipe flange and the Y-Pipe flange. I did not see any type of gasket in this location.

Did you have a gasket between your stock exhaust manifold and the Y-Pipe? If not did you just bolt the two flanges together? Any leaks at this joint?

There is no o-ring.

There should be a triangular gasket with a 3 hole pattern and center cutout for the exhaust pass thru.

Generally its best to order some factory GM gaskets as the headers generally come with crappy gaskets.

Tom

Thanks TMKHUM

Upon closer inspection with a light I noticed the O-Ring is seated inside the Y-Pipe flange. I bolted the two flanges together and after starting did not find any leaks. Time will tell.

GM must have changed there flange seal. I put a set of shorties on my Trans am (aluminum 5.7 liter variant of our 6.0 liter motor) and they utilized the gasket I mentioned. I guess they must have switched up to o-ring donut seal along the way.

By the way what type of gasket was on the exhaust manifold to cylinder head? On the LS1, I have typically seen a 2-layer metal gasket used...pretty good stuff...especially coming from the factory.

Tom

It was a three layer metal gasket.