Landracing Forum
Tech Information => Technical Discussion => Topic started by: Milwaukee Midget on April 28, 2012, 01:58:20 AM
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One for the LSR brain trust.
What is still unanswered is: Ability of these gaskets to withstand between 13.0/1 and 14.5/1 C/R without o-rings.
Anybody out on the site have any experience with Cometic @ these compression ratios?
Thanks in advance,
Fordboy
I off-tracked this one to up the visibility, and hopefully to help others.
I'm running a cast iron block and head, normally aspirated - a BMC A series. But I'd be interested in other applications and observations on the Cometic products.
Of course, the salesman said they're great. But are they better than O-ringing?
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Chris:
Search results from TurboFord.whicheverthisweek :lol: :
http://forum.turboford.org/cgi-bin/ultimatebb.cgi?ubb=search_tng&d=results&record=2456046-020202-CZZV (http://forum.turboford.org/cgi-bin/ultimatebb.cgi?ubb=search_tng&d=results&record=2456046-020202-CZZV)
A lot of crap mixed in, but my quick sampling shows some good info. Some of these guys are boosting 30+psi.
Mike
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There are the standard in NASCAR and the IRL Infinity engines that TWR built ran them without any issues over 10K RPM for 500 miles and that's a lifetime in LSR millage for an engine. Tony
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Too bad that Cometic can't make one for a straight 8 Buick.
Doug :cheers: :cheers: :cheers:
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Too bad that Cometic can't make one for a straight 8 Buick.
Doug :cheers: :cheers: :cheers:
Have you asked them? they may not list it, but I think their ability is endless.
we have used them both o-ringed and non... NA gas, N20 and Turbo, they make a good gasket.
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For Duramax diesel guys only - don't use the Cometic unless there has been a significant change recently. It won't hold as much as OEM will.
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I love mine. They will make them to order for any bore size and thickness.
Most of the Pro Stock Drag Racers use them, and I think they are running somewheres in the neighborhood of 16 to 1 compression with no O-rings.
Just remember, as with any MLS head gaskets its not reuseable after the motor has been fired.
Bob
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Too bad that Cometic can't make one for a straight 8 Buick.
Doug :cheers: :cheers: :cheers:
Have you asked them? they may not list it, but I think their ability is endless.
we have used them both o-ringed and non... NA gas, N20 and Turbo, they make a good gasket.
I would agree with Stainless on that - mine was custom sized, and they were willing to make the bore any size I wanted.
Stainless1, was there anything special you needed to do when you ran them with O-rings? Cometic doesn't recommend it.
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We annealed them, and IIRC only ran rings to about .020 gasket... the .030 didn't displace for the ring and leaked a little water externally. Fairly small rings in small motors of course.
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Stainless, obviously you don't run the MLS (multiple layer steel) gaskets, cause if you try to anneal them you WILL have leaks................. Bob
p.s. On my Early Olds race motor we run Copper with O-rings on the heads only, and have had good luck with them. Ibelieve that I got them from CopperHead, and sent them a stock head gasket for a patern with the bore size increased. I anneal them every time the engine is appart.
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We have run them at BV and they are very good. Except if you want to take a head off, they are one time only. Copper and orings are a better choice IMO.
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The first time I got the answer that they didn't have it in their program. Then about a year later I talked to a different person and they said to send them one and they could do it. I sent one in a reinforced box and paid about $25 shipping and waited and they said that they couldn't make one that long. We use copper now with S/S o-rings. We tried, though.
Doug :cheers: :cheers: :cheers:
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Y'all failed to qualify the question to MLS gaskets.... many moons ago Cometic only did copper... :|
Now that we are on MLS, yep used those also, they worked with our 14:1 1507 busa motor, no sealing problems at all. In fact, in the 13.5:1 1 liter we used Cometic and stock MLS, pulled the center out to make a little tighter squeeze. And we always use copper coat, even if it is not recommended.
added... just caught up on the Midget thread.... now I know you were asking about MLS
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What I'm looking for is an application that is @ 14.5/1 C/R AND 3 STUDS/CYLINDER, using Cometic MLS style gaskets successfully. Does anybody know of any BMC racer running these gaskets successfully?
Thanks in advance,
F/B
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Not to start an argument here about reuse but I have been told by Cometic that reuse is fine as long as the gasket isn't flattened out. meaning the raised portions of the gasket act as springs that do the sealing.
I have reused MLS a number of times but I am not an engine guy per say. I do know that many people do reuse them with and without copper spray and have no issues.
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My motor builder says for street use or hot rods re use was ok,,but he would never re use for race applications.
I guess everyone has opinions on this...me I just buy new ones every time we remove the heads.
CV
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don't know the angles on all the issues about reuse.
I would reference the manufacturer.
cometic has the best gaskets out for v twins.
bf