Reversion ? Head Gasket? Bad manifold ?
 

Ok fellow gear heads.

I'm about to install CMI Headers on my 454. When I noticed some rust starting in the #5 exhaust port of the cast log style manifold I was removing.

Not sure how to deal with this ? I guess I can do a compression check on that cylinder to make sure there isn't a weak spot in the head gasket or chaulk it up as reversion ?

Or ?

Any clues or specifics on what it could actually be ?

Appreciate any facts.

Cheers !

A compression check would be a complete waste of time. Do a Leak Down on that cylinder. Could be an intake manifold gasket as well but probably not.

I would have to believe that the manifold you took off is the reason for the rust. If I read it correclty it sounds like the rust was inside of the port on the manifold. If thats the case i would not worry about it since you are puting new manifolds on. alot of time's the gasket for the rise leaks and causes this. The riser is the elbow that bolts to the manifold. As long as you have the manifolds off you may as well do take the heads off and have them done.