Gaskets or RTV on Exhaust Headers

[Todd Buttrick]

What are people using on exhaust headers between head and headers? I have the FelPro 1415 gaskets for my AFR 185 head exhaust side. The port matching is good for the head side but the four into 4 header side is pretty poor. Thinking I might just use Copper RTV and no gasket. What say the jury?

[Bob Cowan]

The port match is pretty bad. I haven't used a gasket in years, only high temp silicone.

[FF33rod]

Gasket, no RTV.
Sreve

[frankb]

Because my engine needed custom header flanges, I use this stuff- https://www.summitracing.com/parts/php-67006/overview/ and cut my own gaskets. The headers have been off and on twice and no leaks!

[Mark Eaton]

I used copper RTV with the gasket

[skidd]

I blew out one of the provided gaskets after only a handfull of miles.
Decided to give (Remflex 3028 Exhaust Gasket for Ford V8 Engine) a try after reading lots of mustang guys liking them.
Not enough miles (2k) to know if they'll stand the test of time, but so far so good.

[Todd Buttrick]

LOL. There were four possible answers to this question and I got all four in the first four posts. :D. I’m going with Bob on this one for ease of installation. I guess a fifth answer is to use nothing at all.

[rich grsc]

Copper RTV, every gasket I've used eventually failed.

[boat737]

I also have a header flange to head port mismatch. On the advice of Bob (above), I did just the Copper RTV and NO gasket. I have 800 miles since that install 2 years ago. No problems so far. On a side note, I used the 4 into 4 gasket for the side pipes (cut out the little star in the middle) and no RTV. Again, so far no leaks.

[weendoggy]

Percy's. Stage 8 bolts. No issues in 17+ years. No leaks, and, they can be reused.

[CraigS]

I quit using header gaskets years ago. One warning, make sure your flanges are actually flat. Mine needed some work. I used a large flat file moving diagonally so I got marks on the high spots. Then a powered sander to work the spots down. Then back to the file diagonally in the opposite direction from before. A few cycles later they were flat. On mine the ports are a bit smaller than the holes in the flange but offset some. The two gaskets I have tried felpro and Percy's, were both too narrow overall so (I think it was) the bottom only had about 1/8 inch of gasket in use and that is where it always blew out. Using the copper rtv I have the complete header flange sealing to the head.

[AC Bill]

Remflex gaskets since new, going on eight years and not an issue. Percy split-locks for bolts, also still hanging in there.

[Avalanche325]

Copper RTV. I have two studs that I use for alignment. That way you don't smear your RTV around. They have slots cut in them for removal.

[OVCobra]

Ditto on the Remflex, P/N 3083 for AFR heads, port dimensions are 1.38" x 1.40"...use these on my AFR 185 heads, fit is better than any others I have tried. Can buy sheet material and cut your own for the 4 into 4 flange

[Derald Rice]

Ask 28 people and get 28 answers.

For the header, I use remflex gaskets with a thin coating of copper rtv on both sides . Even if remflex says not to use any rtv.

Copper rtv with no gaskets on the side pipe flange.

[jrcuz]

I used Copper RTV, also used ARP studs instead of bolts for the headers.
JR