I've got my car apart, and am about to install my new header... but I can't find anywhere if I'm supposed to use hi-temp silicone in addition to the gasket or not... please advice :-)

I installed my header without any type of sealer. The gasket sealed good but after about 10k miles the "performance header gasket" developed small "cracks or pin holes" creating small leaks. I have seen people use some kind of copper based sealant that is for the high temps. When I replace my gasket I am planning to use this copper based sealant to see if it makes the gasket stronger.

cool thanks :-)

I've never used sealant on any of my header gaskets and I think I remember reading against it.

something else you may want to do is also check your torque settings on your bolts

i found after a few days of driving the car they tend to work there way loose again.

Proper torque! Make sure the header flange is flat! No burrs, welding slag! Two of the best pieces of advice when installing a header on a Z.

I've used two different kinds of gaskets without a sealant of any type with pretty good luck with both. One is the type that is foil covered, it's a paper type gasket, but it has a dimpled foil or metal covering. The best one to use is one that is foil covered with the metal seal made into the gasket.

I would only use a copper sealant if I used one at all, the heat will probably be too much for anything less.

Another thing to look at is the flange thickness of the header. On mine the intake manifold flange was thicker than the header and I had to modify the washers to get equal torque on both.

Quality issues aside, on exhaust joints I use a product available in OZ called MANISEAL.

Comes in a flexible 145g tube.

This is an exhaust cement made by CRC and is also suitable for kiln repairs up to 300deg C.:classic:

but I plan on putting a thin film of the copper antisieze paste on the gasket, both sides. Will use it on the studs and nuts too.

I use VersaChem Type 13, good for 2000 degF.

Use it on all my cars for plugs, SU carb screws; any place where I want to prevent 2 parts heat welding together or from dissimilar corrosion.

Hey where were all you guys Saturday morning when I needed you? ROTFL

I ended up using a thin bead of silicone just around the intake ports on the head side (local shop suggested that). I got everything back together, fixed my high idle (check my other HELP!! thread), and quasi-hung the tailpipe. Sounds good, now I've just got to get it to a muffler shop to hang the tailpipe correctly