How to ensure a good seal with Cometics??
05-07-2008, 11:39 AM
#1
How to ensure a good seal with Cometics?? guys how can I install these head gaskets knowing that im not going to have any leaks? I read ALOT of people having leaks with cometics. Im about to return the ones I got and just use GM MLS. Im actually scared to use them after what I read. Do you guys reccomend that copper spray?
05-07-2008, 11:50 AM
#2
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We generally recommend a good copper spray. Also the finish on the block and heads are vital. If the heads and block were properly decked you should not have any issues. Cometic usually recommends a surface finish of 22 RA or smoother. Our CNC gets blocks and heads between 11 and 14 RA. For comparison glass is approx a 5 RA.
05-07-2008, 12:05 PM
#3
I've done this only once FWIW, but I have an 02 that had MLS HG so it was easy to get the deck ultra clean. The heads were new. I even wiped the surfaces with brake cleaner so that there was no oil film. I installed them dry and haven't had any leaks.
05-07-2008, 12:12 PM
#4
We generally recommend a good copper spray. Also the finish on the block and heads are vital. If the heads and block were properly decked you should not have any issues. Cometic usually recommends a surface finish of 22 RA or smoother. Our CNC gets blocks and heads between 11 and 14 RA. For comparison glass is approx a 5 RA.
05-07-2008, 12:34 PM
#5
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Really just a precaution more than anything. We really picked that up from the Turbo Buick's which had huge H/G problems with the Cometics. Our long blocks do not have these issues. The copper spray isn't going to hurt anything, may just make it a little messier. Again it is mainly a good precaution to make sure everything is sealed as much as possible.
05-07-2008, 12:39 PM
#6
benefits of using copper spray
Jim
05-07-2008, 04:09 PM
#7
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I've done 3 engines with cometics and the copper spray and none of them leaked. I was worried like you after seeing the leaking posts but they were always good gaskets to me. Never used them on a boosted setup though.
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05-09-2008, 12:50 PM
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I was running copper gaskets before and coated them with copper spray and they never leaked.. Now I'm running Cometics on this new motor also coated with copper spray and no leaks so far. Haven't been to the track or used the nitrous yet.
05-09-2008, 01:48 PM
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I used a set for 3 dyno pulls and 4 passes down the 1/4. I asked Cometic if I could reuse them. They said no, not once they have been heat cycled. Damn waste of $150. Anyways, once I tore it down to forge it, it was leaking combustion on 1 cylinder. Fresh heads on a not decked block does not work very well with Cometics. They need a perfect surface. Nothing major, but that was NA. I would hate to think what 10 lbs. of boost would have done.
05-09-2008, 02:51 PM
#16
I used a set for 3 dyno pulls and 4 passes down the 1/4. I asked Cometic if I could reuse them. They said no, not once they have been heat cycled. Damn waste of $150. Anyways, once I tore it down to forge it, it was leaking combustion on 1 cylinder. Fresh heads on a not decked block does not work very well with Cometics. They need a perfect surface. Nothing major, but that was NA. I would hate to think what 10 lbs. of boost would have done.
Can you deck an LS1? I know you cant really bore them very much, just curious about that.
