Which head gasket?
Thread Starter
Burning Brakes
Joined: Sep 2005
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From: Temple TX
Which head gasket?
Which head gasket should I get? I am adding AFR 205s with 66cc, with MTI X1 Cam, LTs, full exhaust, FAST 90/90, and Wet 150 shot. Want to bump the compression some. Thanks
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
You can pick your gasket thickness with the Cometics, but I didn't like their frequency of leaking so I went with the GM MLS gasket. The 6.0 is a little thinner but has a slightly bigger bore.
Race Director
Joined: Sep 2005
Posts: 11,060
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From: Pasco WA
Probably should have had your heads milled to about 60cc or so, but you don't want the larger bore gaskets,(6.0) especially if you're gonna spray. Go with the .040 Cometics and use copper spray, and they should seal fine.
Safety Car
Joined: Jan 2004
Posts: 3,786
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From: Houston TX
Has nothing to do with income and sig's for me. I'm using .040 gaskets to improve the quench and bring my scr and dcr into the sweet spot for my cam/heads combo.
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Burning Brakes
Joined: Aug 2006
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From: Shreveport LA
Should have gotten the heads milled a little bit more and saved the extra $130 over the cometics, the extra 3-5hp difference isn't worth it unless you just want to spend money on more expensive gaskets and chance the headaches of getting them to seal.
Safety Car
Joined: Jan 2004
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From: Houston TX
Milling will not help the quench and we are more concerned with under the curve torque that a setup with optimal dcr will produce.
Last edited by Allthrottleandsomebottle; Dec 30, 2006 at 08:27 PM.
Burning Brakes
Joined: Aug 2006
Posts: 789
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From: Shreveport LA
The only thing effected by cometics over milling would be quench which has not been proven to add much if anything, you can always do a search at ls1tech if ya think it does. That's why I said 3-5hp The original poster asked which gasket and I was just stating my opinion on the subject.
Last edited by Allthrottleandsomebottle; Dec 30, 2006 at 08:27 PM.
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keep it on topic........or start your own thread
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
I would personally do some milling to get where you want and then use the GM MLS gaskets. They are much more forgiving. I would also use the ARP studs as suggested above making sure to get the ARP Moly Assembly Lube so that the correct torque procedure can be used.
Thread Starter
Burning Brakes
Joined: Sep 2005
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From: Temple TX
I have the ARPs, but do not really have anyone close to mill them and dont want any down time.
Racer
Joined: Mar 2006
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From: silverdale washington
Lets think about this, youre gonna mill heads to get that couple of horsepower. Except now that your heads are milled they flow a few less cfm. Pissin in the wind if ya ask me. wastin time and money.
Race Director
Joined: Sep 2005
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From: Pasco WA
Totally disagree. The thread starter wants the best gaskets for his application, which will include NO2. Gas likes high compression, as do these LS engines, even NA. NO2 also prefers a tight quench, which also helps DCR, which also builds TQ. Since milling is out of the question, the only thing that does what he requires, is thin gaskets. BTW, the Cometics are also MLS, and are well proven to not leak if installed correctly.
Racer
Joined: Mar 2006
Posts: 464
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From: silverdale washington
Not sure I understand what your disagreeing with. No doubt all motors definitely like compression. However Im saying milling the heads is not a great idea. when you mill the heads they will flow less. Which is way more important than any other aspect of your motor. Your motor should be built around the heads. not vice versa. Great if you have a ton of compression but if you cant get fuel in what does it matter. If you really want to build a high compression motor, Then do it right and use the correct piston or deck the block. I think vipers on the right track here w/ 66cc heads. I would use gm mls head gasket as I have never had one fail. But dont get caught up w/ the static compression ratio, focus on the dynamic which im sure will already be bumped substanially w/ your camshaft.
Safety Car
Joined: Jan 2004
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From: Houston TX
Viper with your X1, 66cc heads and stock gm MLS gaskets your scr is 10.37:1 dcr is 7.95:1. Most builders recommend a dcr of 8.2 to 8.6 to run on 93 octane. If you go to a .040 gasket your numbers go to scr 10.67 and dcr 8.17.
Burning Brakes
Joined: Aug 2006
Posts: 789
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From: Shreveport LA
Oh he posted how much his pistons sit out of the bore? Without that you can't figure the accurate numbers. Cometics are nice if you want to squeeze every little bit out of the motor and just want to blow an extra $130. If you don't want to get the heads milled or can't I would get the cometics then. Changing my tune a little after he said he couldn't mill.