Saw the thread on intake manifold gaskets and thought I would cover the other side of the head. What are you guys using for gaskets when running headers? I am running Lightnings on my engine. Are the copper gaskets worth the money? What about sealant - is anyone using the red high temp RTV on them?

I just use rtv high pressure which is also high temp if you read the tube. No gaskets. But I'm running Stainless Marine Manifolds that have a machine surface. With a header I would use a gasket.

If I can sidetrack this for a second, can anyone tell me the best place to order 525 header gaskets from? I pulled my headers to pressure test and the gaskets are not reusable. Thanks.

The absolute, hands down, best exhaust gasket is a Cometic Multi Layer SS gasket. They are a little pricey, but well worth it. They are basically a lifetime gasket. If/when the header comes loose and starts to leak, a normal gasket will blow out. At that point you need to remove the header to remove all of the gasket, replace it with a new one, and bolt it all back up. With the ML gasket, just tighten up the header and the leak will go away. It's virtually impossible to blow the gasket out. They can be removed as many times as you want and just put them back on. I have some that have been in service for over 8 years now and have been off and on numerous times.

Recently, I had Cometic make a gasket with both the 525 pattern and a standard BB pattern. That saves me from stocking 2 different gaskets. I usually still keep the standard BB gasket since it is cheaper than the dual pattern one. However, the dual pattern gasket is much nicer. It has 5 thick layers of embossed SS. The standard gasket is only 3 layers of embossed SS.

I've attached a pic of the standard BB ML gasket. I have some of the dual pattern gaskets on order. I just sold the last 2 sets last week, so I don't have one to take a pic of. The standard gaskets run around $50 a set and the dual pattern ones for the 525 run around $80. Hell, a stock set of 525 gaskets are almost $60 from Mercury, and anyone with a 525 knows they don't last.
Eddie

x2...

They look expensive!!

SInce they have issues blowing out, do you think some water reversion / ingestion issues stem from this but blamed on a leaking (water internally) header ? Exhaust leaks at the flange gasket have been known to cause reversion.

Why would exhaust gaskets blow out if you make sure the bolts are tight? Mine lasted for years and I had to pry the headers off which tore the gaskets in half. I wonder how much the Cometic ones cost. Guess I'll call around.

I did not know about those gaskets , thanx for the heads up EDDIE!

It's certainly possible. What I meant was that the headers eventually come loose. If you don't catch them in time, the exhaust pressure will push the gasket out. Once it does that, the gasket is junk. You have to continuously check the header bolts, especially if they were recently taken off.