Cometic headgaskets

[SHADOW]

I put a set of Cometics on a buddy's car. We fired it up to break the motor in and it started leaking water on the outside back of the head. We torqued the ARP bolts to 70lbs. Should they be torqued more? I was told these gaskets go on dry, which i did.
What do you guys think i did wrong? TIA

 

[Russ Merritt]

I have GN1s/Cometcs and torqued to 80 ft/lbs. No leaks. You sure it's the HG? Gm seal tabs to the rescue.

 

[SHADOW]

There's definately a little bit of water in the oil. I'm pretty sure it's the head gasket. Leaking from same place on both sides.
Guess i'll retorque the bolts and see if they moved.

 

[V6 Beast]

Since the Cometics are non-compressable, I would think the heads and block deck would have to be pretty darn flat. Did you have them checked before putting the heads on?


Sully

 

[Trevor Johnson]

Cometic head gaskets require that both the head and block surface be flat and very smooth. Cometic recomends dry installation, I have had customers use them on many cars and had best luck using a thin spray of copper sealer on both sides to ensure no fluid leakage. They are great gaskets but are not forgiving to rough machine work. If you can eaisily drag a fingernail on the surface finish of the decks you should use sealer as insurance. These gaskets are supposed to be re-usable so you could just clean them and the surfaces with laquer thinner and seal the engine up. Good luck.

 

[SHADOW]

We had the heads surfaced and the block looked pretty good. I'm gonna try the head bolts at 80lbs. If they still leak, i'll take em off and use the copper sealer. Thanks for all the help!

 

[19TTA89]

Where can you get these cometics from???

 

[V6 Beast]

www.cometic.com. They come in verying thicknesses. The .057 is the thickest before the price skyrockets even worse..


Sully

 

[Russ Merritt]

Champion has em. 56$ a piece, .040 thickness compressed, part # C5691

 

[V6 Beast]

$56 is a good price.. But why not get the .057 since they are closer to the stockers. Stockers are .060 right?

Sully

 

[Russ Merritt]

I wanted the thinnest gasket so it was harder to push. Less area (thinner) the harder to blow. Not much differance between the 2 really.

 

[buickboy]

Been running them with great sucess and no leaks for 6 mos. I use ARP bolts and torqued them to 85 lbs. no retorque. no sealer on the gaskets, and no GM tabs necessary. They are Viton coated already. $56 is a good price. Also get them through cvproducts.com good luck
Mitch

 

[SHADOW]

They're sealed now. I retorqued to 85 and put a couple pills in just to make sure. No more leaks.

 

[Not Avg 6]

Mine are great so far. but only after a couple of weeks. Have seen 20psi accidently for a quick moment though.