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i have a 383 with 31cc dished pistons, custom grind schnieder cam, le2 heads and plan on running about 8-10 lbs of boost. With the stock f body gasket thickness it will be 8.8 to 1 compression ratio. would cometic gaskets be a better choice than stock fbody ones? Anyone with experience either way please chime in.
thanks!!
Ron..
 

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I always use copper head gasket on Boosted. If I plan to go over ~14 psi I O-Ring the block. Pay me now or pay me later I have never seen anyone have a problem with copper anything else has had problems.

On an LT1 they now have a thin copper gasket that I think is ~.042"

Good luck
 

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I always use copper head gasket on Boosted. If I plan to go over ~14 psi I O-Ring the block. Pay me now or pay me later I have never seen anyone have a problem with copper anything else has had problems.

On an LT1 they now have a thin copper gasket that I think is ~.042"

Good luck
i've had a problem with copper gasket... wouldnt seal. (block not oring'ed)

installed some Cometic gaskets and it was perfect.
 

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i've had a problem with copper gasket... wouldnt seal. (block not oring'ed)

installed some Cometic gaskets and it was perfect.
A few probable reasons are: your head or block is not true, you didn't use silicone at water ports, or didn't torque properly. Cometics will cover differences better than copper but they cometics won't hold as much as boost as copper.

Did you deck block and surface head before using copper? Did you blow a head gasket then go to coppe?

As I said pay me now or pay me later.
 

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head and block were decked, all was perfectly clean, I have ARP head studs.

I did not use silicone, but they were rubber coated copper gaskets from SCE if my memory is correct.

My engine builder told NOT to use them, that they often leak... but I already had them and decided to try them out. They did exactly what the builder said they would do, leak.

@ WOT the engine would fill the water jackets with air and it would leak coolant by the expansion tank cap. If i drove normaly, no problems... as soon as I go @ WOT it would overheat and spit coolant by the cap.

I lifted the heads, dropped in Cometic gaskets and problem was solved. My engine builder also uses Cometic on his 1000+hp engine with great success. He said copper works better with an o-ring'ed block but he prefers Cometic.

The engine I am building for turbo application will have freshly machined deck & head surface, ARP head studs and Cometic MLS gaskets :)
 

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Well you are the first I know that had trouble with copper in an LT1.

In an LS they claim because of the head bolt configurtion three layer cometic help prevent leaks. But in an LT1 IF you decked the engine and head I can't see how it wouldn't seal if the head was torqued properly. From your data copper don't work and I know that is false.

Friend runs a machine shop he has never had a customer have a problem so...
 

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From your data copper don't work and I know that is false.
No, thats not what I said.

You said that you never heard about anyone having a problem with them... I'm just telling you I did.

All I say is that I had a problem with the copper gasket and that Cometic works for me.

Cometic worked for me, copper works for you... I just wanted to point out that copper isnt the only good solution out there. The MLS also works great on several very high hp cars I know of. And yes, I know of some high hp cars with copper gasket that seal just fine also ;)
 

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Just my .02 cents, at the shop I have seen some high hp blower cars and high compression race motors....with a nicely milled head surface and deck, we haven't ever had problems with MLS and our engine builder says he's been using them for a while... Granted, ANY imperfection and MLS isn't going to seal well...but imperfection in head/deck mating surfaces and forced induction don't belong in the same sentence. Making sure the heads and deck are true and flat and the surface is machined to a nice texture is the first and foremost thing that should be done.
 

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use cometic, i have a twin turbo lt1 with afr heads. i never had a gasket problem. i ran 26 psi of boost.
what? and you tell us just now??? :p


got pictures? details? what turbos? tuning software? fuel delivery?
care to share? it would be very much apreciated. cwm7
 

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ARP studs & Cometic head gaskets here.
 

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what kind of car are these numbers off " big purple " an f-body?

oh and cometics FTW always never had a problem with MLS gaskets with a little copper sprayed on both sides with some arp heads studs and teflon paste your good to go.

and on the 1074's they will work fine just make sure you purchase no bolts or studs dont cut corners if you dont have them already.
 

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here are some links. http://www.ls1tech.com/forums/lt1-lt4-modifications/1061089-8-55-169-9-mph.html

http://www.gmhightechperformance.com/features/0711gm_1996_pontiac_trans_am/index.html

since all of these accomplishments with my lt1 i am selling all of my lt1 parts and switching over to a traditional sbc so i can run on the outlaw 275 dragradial circuit. i still have the best pair of afr220 comp ported heads with jesel pro shsft mount 1.6 ratio rockers and a meziere heavy duty lt1 water pump i need to sell. if any one is interested i can be reached @ [email protected] or by phone 225-445-1534 my name is omar.
 

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OK, I'll ask. So why did you not go the LTX shootout in KC for the last two years? It's Camero Fest for sure so you would have fit right in and should have won it with a 8 as none were going that fast.

Just keep in mind what the Impala's weigh and the affects to ET/MPH that has. Still guessing you were making about 1250HP with an LT engine which is very respectable. Good info on what your were using as the heads start to walk a little in that HP range.
 
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