[CraigG.]

Hey Everyone,

When sealing a header flange to a head which is better Permatex RTV red high-temperature Silicone sealant or Permatex Ultra copper high-temperature Silicone sealant?

Thanks, Craig

[johnta1]

I use the copper one. Seems to withstand the heat longer.

[CraigG.]

I also wonder about the Permatex red RTV that is the Right-Stuff or Ultra-Red that's both have temperature rating up to 650?

[mysticmissle]

i have used a few different types i am a big fan of dow 737 it is the best sealant i have used for almost any application including headers. High or low temp doesnt not seem to matter for header usage. IE copper doesnt matter in my experience.

[firechickenman]

I've always used Ultra Gray. Several years with no issues. If nothing else, it's not as noticeable with aluminum heads and silver headers.

[MatthewKlein]

In my experience. Keeping the bolts from backing off is the most important thing. Many companies make kits with clips and washers. The easiest for me was safety wire. I've never had a leak if the bolts were tight.

[CraigG.]

Over the years of using copper gaskets with sealers and after trying many options of combinations of gaskets - My old machinist planed flat the flange and then I used the ultra copper without gaskets. - mufflers on the street and open headers at the track.

They are leaking now - do using mufflers and the resultant backpressure indicate a more comprehensive approach - like special gaskets, etc?

Thanks, Craig

[turbo69bird]

I always use ultra copper w turbo applications these get crazy hot and have lots of back pressure and it works , regukar headers I’ve never had it fail

[VCho455]

Originally Posted by CraigG.

- My old machinist planed flat the flange and then I used the ultra copper without gaskets. - mufflers on the street and open headers at the track.



Thanks, Craig

It can't be over emphasized how important having the gasket surface(s) flat and true is to having trouble free headers. No leaks, no loosening fasteners. It's worked for me on Pontiacs, AMC's and Chevies. Race cars and daily drivers.

I use a 4 foot long belt sander to get mine perfect.

[Mr Twister]

If you are running EFI or a stand alone sensor, Make sure what ever you decide to use, that it says its safe for 02 sensors.

[455dan]

Had better Luck just going with Remflex gaskets than multiple tries to seal with sealant a warped header flange. Do have to be gentle with them during install though.

[John Langer]

I use red or orange.

[RAIV-Z]

I've used ultra copper without gaskets.

[turbo69bird]

I use ultra copper w wide band O2 all the time never had an issue. . Same O2 sensor in my car since 2009

[CraigG.]

Thanks Guys - I will try this:
Permatex 27038 Optimum Red High Temperature Gasket Maker, 3 oz

[CraigG.]

The Copper is good Too!