I hand cleaned my deck surfaces and sprayed my .040 cometics with 2 light coats of copper spray and torqued the studs down to 85 lbs and never had a leak.

 

The Cometic comes with a sealer on it (its black). The instructions specifically say do not use the copper spray as it interferes with the sealer on the Cometic. I followed Cometics instructions had no issues.

 

thats weird, is that new? how long ago did you see that note on the cometic gaskets NOT to use copper spray? interesting.

 

I do not remember having sealer on mine cometric gaskets.
I used copper spray and no leasks. Knock on wood......

Bill

 

That has been the case since day 1.
A lot of us spray lightly and no issues, better than leaking 50% of the time.

 

I haven't had any problems with mine. Didn't spray them with anything, just spent a long time cleaning the surface of the block and installed new dart heads with ARP bolts and moly lube.

 

Holy old thread.

I'll add my 2 cents though. 2 years in a row 2006 and 2008 my .040 cometics began to leak from around the #2 cylinder. LGM did the work and I can vouch that they did a good prep but never the less the cometics leaked. No copper spray used, just cleaned the block and heads very well. Upon examination of the gaskets it was found in both incidents that gasket area toward the front part of cylinder #2 had imperfections at the point of the leak. A mystery I guess. Switched to gm mls and gave up a bit of compression and problem solved. GM mls were used on my 402 and 2100 miles later no leaks !!! LGM was not the problem, I guess I got 2 bad sets of cometics. ???

 

or, maybe thats just more evidences its a good idea to USE the copper spray. dads havent leaked yet. I used a liberal dosage of copper spray gasket. although the car is still tucked away in storage so far this year. but there wer no leaks at the end of the year last fall.

 

I used Hylomar spray, which is designed for this type of use. Just a quick dusting as it will seek imperfections during assembly. I spoke to Cometic before using and was given a thumbs up (as long as you don't go crazy with it.

I also was fortunate to have a Profilimeter from work to check Ra values and I bought a Snap-On machinist level to check flatness of the heads and the block.