I have good luck with:
RTV used as manifold end seals - if done right, no leaks and no intrusion into the engine.
Regular gaskets - installed per the mfgs instructions.
Permatex Aircraft adhesive - If I have a gasket that I want to stay in place, like an oil pan gasket to the block, I use this to stick it and leave the other side clean.
1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.
