harpelt

I have been blowing out the gasket between the engine and the aftermarket header on one side. I just replaced it today and within a few miles of driving it blew out a section again. Any ideas for a fix?

Engine is a 350 in my 68 cutlass holiday coupe.

svnt442

If this happens on a regular basis you might have a warped flange. That is the usual cause of this type of blow out and is very common on cheaper headers due to the thin flanges on them.

wr1970

I just use hi-temp rtv. What gasket lol.

76olds

Maybe you could try a set of Remflex gaskets, I've had them on my 76' 350 with hedman headers for a few years now with no problems, although my low compression 350 likely couldn't blow out any gasket haha. If Hi-temp rtv that Nealey mentioned works well, that would be much cheaper than the Remflex gaskets.

Eric

Fun71

I use regular Fel Pro exhaust manifold gaskets and they hold up very well, but as said your flange is likely warped.

ELY442

Make sure you scrape off the leftover gasket. Use a razor blade and go over the ports on the heads and headers. I apply a coat of Hi Temp RTV on both sides of the gasket. I haven't had a leak yet. Good luck.

wr1970

From what i was told i think Joe P also posted this before!Factory had no gasket.

FStanley

Another vote for Remflex, they make divider and non-divider ones FYI.



YEah YEah Yeah make sure both sides are clean, I took a big file and files a bit on both sides to see high spots, then wrapped 220 grit sandpaper around file to clean up surface, cleaned with acetone squeaky clean.

Mine were blowing out at the bottom, took the remflex and used the big file again to take off a little material at an angle to make more narrow at bolt up holes, to make it tighter at the bottom..


note only torque to 20lbs, usually 5 less then stock so you do not over crush... no goop added.. not convinced RTV would hold up under constant hi temps Remflex tout 3000 deg temp spec..

recheck torque values after 1st heat cycle, then after a month, then after a year. to make sure...


Look at mopar 440ci. guys posts...

Now all OK after SEVERAL,FREQUENT, ONGOING, WOTs!!!!

oldsmobiledave

Remflex & don't over tighten. 20 ft lbs only.


Works for me.

Fun71

Factory used cast manifolds and not headers.

wr1970

What difference does that make? Flush fit is a flush fit.

64Rocket

I always double gasket when using headers.

Gene

Kennybill

X 2 on the double gaskets with headers

oldcutlass

Sometimes you have to experiment with gaskets, there are some on the market that are made for your situation where there are gaps and the gaskets crush into place to seal.

svnt442

It goes back to what I said about the flanges. The cast iron manifolds are very stable in regards to warping and they didn't see the need for a gasket. With the thin flanges on most headers they tend to warp very easily.

wr1970

What ever you think. I used RTV as mine are not warped.Mine was checked before i installed them heads and headers. After Joe P said what he said i could find no reason to use a gasket and create a warped condition/ leaks. Metal to metal is more stable.JMO

oldcutlass

You are one of the few if not the only one who got headers to seal without gaskets.

wr1970

Maybe you should try it. Just remember i didn't buy a paper thin header.I also ended up with a set of headers that had been sealed with RTV. I didn't think anything about it till Joe P started talking about the factory not using gaskets.These were the Jerry Worblewski headers that i am talking about. These were on the tube chassis car that i now own.

ELY442

The OP is referring to blowing out his "header gasket" not factory exhaust manifold gasket.

oldcutlass

And wr1970 is talking about his headers... He stated no gasket, just some blue rtv,

olds 307 and 403

With the 3/8" flange, RTV is no problem especially on Sanderson headers, as that is how they are designed. The cheap, thin flanged headers like Flowtec, I needed double gaskets after the first engine swap or there was seepage when cold.

wr1970

TTT for ref on bbo thread.

brownbomber77

Copper gaskets... Love those things

Run to Rund

I make sure the flange is flat, and use Summit 111440 copper header gaskets.

olds 307 and 403

On cheap headers, the Summit Copper gaskets leaked. I bet if I coated them with high temp RTV, they would have sealed. I had that issue with stainless mls collector gaskets, coated them with Copper RTV, all good.