Exhaust Leaks at Header

[cdog]

I just put my motor back together and I have big leaks at the header/cylinder head connection.

The exhaust is what came with my SPF and the heads are Edelbrock 460 RPM heads.

I put the gaskets on with the numbers facing away from the motor.

When I looked at the new gaskets I bought to fix the damn leaks, I realized that if its put on backwards, it moves the holes slightly, perhaps affording a better fit. Is backwards the right way?

My other option is to use NO gasket and just hi temp silicone.

Any thoughts?

[cwmcobra]

The recommendation from my kitbuilder is to throw away the gaskets and use Copper RTV. Says the gaskets will last one season max and the RTV will last for several seasons. No experience yet, but that's what I plan to use.

Good luck!

[craigayl]

I used Permatex, black hight temp RTV on 3 installs now. After a combined milage of 6000, all is fine.

If you have used gaskets, you need to make sure the header face is not warped around the mounting bolts. If it is, Permatex may not work.

[speed220mph]

cdog
If the headers leak immediately after installation, something is wrong--holes don't match, header flange/s is not straight, bolts are not tightened gradually . . . ? But if your engine runs without leaks for a while, the challenge is to keep them sealed.

First off, nothing will work if the header flange isn't good and flat. Check it with an accurate straightedge to make sure. As for RTV silicone, it works regardless of whether it's hi-temp or not. A Winston Cup engine builder friend of mine will second that. He tosses the gaskets and uses silicone sealer only. Another solution to preventing header leaks due to loosening bolts is to drill the bolt heads with a 1/16" drill and safety wire them. That will keep them from backing out. Both have worked for me.

[cobrashoch]

A old hot rod trick when the mating surfaces are rough is to use two gaskets and studs. Done this several times in the past and it allways works. Makes it simple to tighten the nuts up from time to time to keep those pesky leaks from coming back. As for how long they last, my neighbors car is a daily runner w/130K miles on his headers using Hooker supplied gaskets. Caution - You will loose that hollow header "sound" using this method. It really quiets them down. This is the only way to fly in my mind on cars that have side pipe attachments, as silicone will eventually work itself loose with side pipes that force header flex from engine torque rollover.
cobrashock

[Mr.Fixit]

SPF built some 460 headers a few years back with the flanges an backwards. That caused restricted exhaust and premature leaks. Look at your header flanges, gaskets, or heads, notice that the bolt holes are not the same distance from the pipe on each cyl's exhaust. The bolt hole on the left of each pipe is further away than the bolt hole on the right side of each pipe.(or is it the other way?) Make sure your header flanges are correct in this aspect, as well as your gaskets orientation between them. If you use the paper/foil header gaskets, you will leak. I like the blue Fel-Pro ones. After a heat cycle or two, retighten your header bolts. You will need to do this a couple of times until they take a "set".

[Lumberman]

I had similar problem using SPF headers with Edelbrock aluminum heads on FE motor. Discovered that top of bolt flange on header made premature contact with head preventing proper contact between header, gasket and head. We ground off just a little of the flange to create extra clearance and problem was solved

[Cobranut]

I used the embossed copper gaskets from Summit or Jeg's.
I can't remember the brand name right now, but I made sure the flanges were flat, put a thin coat of red RTV on each side, installed them with stainless studs, and have had no problems.

Good luck,