I'm sure that this has been discussed many times, but please bear with me.

When I replaced the 390 in my 64 Galaxie with a reman engine from S&S, I also bought a set of nice stock exhaust manifolds on E-Bay. I had them sandblasted and the mounting surfaces machined flat then coated them with POR hi-temp gray paint.

For whatever reason, when my mechanic assembled and installed the engine, he used the FelPro exhaust manifold gaskets that came with the engine. I never really paid attention until about two months ago when I developed what sounded like an exhaust leak at the manifold/heads. I retorqued the manifold bolts and the leak went away. The next time the car was in the shop, I had him retorque all the exhaust manifold bolts. Eveything was fine until a few weeks ago when the noise came back (kind of a soft "chuffing" from around the manifold bolts that changes with rpm and quiets down some as everything warms up), although I haven't been able to exactly locate the source (need to pick up a stehoscope).

Anyway, I have purchased a set of the copper exhaust manifold gaskets to use in place of the Felpros if I determine them to be the problem. So two questions:

1. Not knowing how long it takes the hot exhaust gases to erode or warp things, are the copper gaskets my best bet for sealing things up?

2. Should I use any hi-temp RTV on either side of the copper gasket?

I hope to install a set of Sanderson 390 headers next year, so I don't really want to replace the stock exhaust manifolds, and since they have been machined once already, I don't think they could be machined again.

Sorry for the long post.

 

I installed a set of Summit copper gaskets on my '89 w/5.8l a while ago. It has Summit shortie hedders on it and they are holding up well so far. I installed mine dry without any sealers. I don't think a sealer would help. You do need to retorque after a couple warm ups to help seat the bolts and gaskets. Use antisieze on the bolts.

 

I'd use the copper gaskets along with some Permatex Copper Spray-A-Gasket. It's supposed to be good for stuff like that.

 

I have had good luck with these on my stock truck manifolds
http://www.pickproparts.com/PartsLis...ategoryID=5400
Look up the gaskets under 1975 F100 ford with the 360 and then exhaust manifold gaskets .

You can use BOTH gaskets together > I have no leaks with just the shield type gaskets .'
Might be the cheepest route.

 

The FelPro gaskets I have are what appear to be leaking. My application doesn't use a heat shield. I already have the copper gaskets to install if necessary.

 

the heat sheld should work on your application but if you have the copper gaskets then by all means use them.

 

Thanks to all.