Best Lt1 head gaskets
Joined: Nov 2001
Posts: 10,023
Likes: 6
From: LT1 land...the "409" of the 90s!
I checked on this a while back.
DO NOT put FelPros back on. Call SDPC and get some Cometics. Those and some ARPs. I am coming out of the hole on a #82 jet and took out my FelPros. All the big boys told me to go to Cometics.
BTW If you lower the compression you just have to run more juice to make up for it . No myth there
DO NOT put FelPros back on. Call SDPC and get some Cometics. Those and some ARPs. I am coming out of the hole on a #82 jet and took out my FelPros. All the big boys told me to go to Cometics.
BTW If you lower the compression you just have to run more juice to make up for it . No myth there
Staging Lane
Joined: Feb 2006
Posts: 80
Likes: 0
From: St. Charles, IL
I want to know who is using what type of head gasket/Bolt or stud combo?I have the heads off of my 383 right now because they lifted and it was pushing compresion into the cooling system. AGAIN! What came off of it was Flat-out head gaskets and ARP bolts. ON motor it is fine .When I spray it with 150 shot I start having Problems. I think I will go with Cometic head gaskets and ARP stud kit . What has everyone had the best luck with. Mainly interested in Head, Compression , engine size and whether or not you are using nitrous.
As mentioned earlier, Cometic gaskets require a specific "smoothness" on both the cylinder head and deck of the block. Unless you know for sure that they have been machined with this in mind, I wouldn't choose the Cometics for a replacement. Most people have choosen Felpro 1074's and don't seem to have any problems with them. If it is feasible, I would consider head studs and pay close attention to ARP's torque procedure AND the recommended lube to use on them...it makes a tremendous difference.
Thread Starter
10 Second Club
iTrader: (6)
Joined: Mar 2007
Posts: 952
Likes: 0
From: Fuquay Varina, NC
Can you be more specific about the head gasket problem? You say the motor is lifting the head which is unusual for your combination. If this is what is actually happening, a new gasket isn't going to fix the problem. What does the head gasket look like after you notice the problem?
As mentioned earlier, Cometic gaskets require a specific "smoothness" on both the cylinder head and deck of the block. Unless you know for sure that they have been machined with this in mind, I wouldn't choose the Cometics for a replacement. Most people have choosen Felpro 1074's and don't seem to have any problems with them. If it is feasible, I would consider head studs and pay close attention to ARP's torque procedure AND the recommended lube to use on them...it makes a tremendous difference.
As mentioned earlier, Cometic gaskets require a specific "smoothness" on both the cylinder head and deck of the block. Unless you know for sure that they have been machined with this in mind, I wouldn't choose the Cometics for a replacement. Most people have choosen Felpro 1074's and don't seem to have any problems with them. If it is feasible, I would consider head studs and pay close attention to ARP's torque procedure AND the recommended lube to use on them...it makes a tremendous difference.
Thread Starter
10 Second Club
iTrader: (6)
Joined: Mar 2007
Posts: 952
Likes: 0
From: Fuquay Varina, NC
Nitrous likes compression.
The "impala" .029 gasket might be worth considering if you do want to try and get quench right.
Cometic has a .027 IF the surface finishes are perfect, they have a lot of options actually.
I listed the .026 gasket PN above but I don't know if I would try and pull quench down that far.
You running a dedicated system for enrichment fuel?
The "impala" .029 gasket might be worth considering if you do want to try and get quench right.
Cometic has a .027 IF the surface finishes are perfect, they have a lot of options actually.
I listed the .026 gasket PN above but I don't know if I would try and pull quench down that far.
You running a dedicated system for enrichment fuel?
I would then wonder if a momentary lean at the hit [plays into this as well.
If you go too a small dedicated system you can use a low pressure carbed deadhead style pump and regulator for reasonable money and put as high an octane unleaded as you can find in there.
That was a thick gasket you were running, any idea on the bore. Wondering how much compression will be raised going too a thin gasket.
If you go too a small dedicated system you can use a low pressure carbed deadhead style pump and regulator for reasonable money and put as high an octane unleaded as you can find in there.
That was a thick gasket you were running, any idea on the bore. Wondering how much compression will be raised going too a thin gasket.
Staging Lane
Joined: Feb 2006
Posts: 80
Likes: 0
From: St. Charles, IL
Is the block o-ringed and the head have a receiver groove? I've never known anyone to have any luck sealing a copper head gasket at the combustion chamber without these. From Flatout's website:
How do I prepare to use Copper Head Gaskets?
We recommend that all copper head gaskets be installed on engines with machined "o-ring" grooves and stainless steel wire o-rings. This groove is traditionally done in the engine block. Typical wire diameter is .041" in a .039" wide x .029" deep groove resulting in a wire standup of .012". This is used in combination with a .040" thick copper gasket (about 4 times the wire standup). For engines at or above 3 HP per cubic inch of displacement, the combustion seal should be enhanced. For this we recommend a receiver groove opposite the o-ring, typically in the cylinder heads. See your engine builder for other options and machining details
How do I prepare to use Copper Head Gaskets?
We recommend that all copper head gaskets be installed on engines with machined "o-ring" grooves and stainless steel wire o-rings. This groove is traditionally done in the engine block. Typical wire diameter is .041" in a .039" wide x .029" deep groove resulting in a wire standup of .012". This is used in combination with a .040" thick copper gasket (about 4 times the wire standup). For engines at or above 3 HP per cubic inch of displacement, the combustion seal should be enhanced. For this we recommend a receiver groove opposite the o-ring, typically in the cylinder heads. See your engine builder for other options and machining details
Staging Lane
Joined: Feb 2006
Posts: 80
Likes: 0
From: St. Charles, IL
From the Cometic website FAQs:
What surface finish is required to us an MLS head gasket?
A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design.
What surface finish is required to us an MLS head gasket?
A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo Thread Starter
10 Second Club
iTrader: (6)
Joined: Mar 2007
Posts: 952
Likes: 0
From: Fuquay Varina, NC
I would then wonder if a momentary lean at the hit [plays into this as well.
If you go too a small dedicated system you can use a low pressure carbed deadhead style pump and regulator for reasonable money and put as high an octane unleaded as you can find in there.
That was a thick gasket you were running, any idea on the bore. Wondering how much compression will be raised going too a thin gasket.
If you go too a small dedicated system you can use a low pressure carbed deadhead style pump and regulator for reasonable money and put as high an octane unleaded as you can find in there.
That was a thick gasket you were running, any idea on the bore. Wondering how much compression will be raised going too a thin gasket.
Thread Starter
10 Second Club
iTrader: (6)
Joined: Mar 2007
Posts: 952
Likes: 0
From: Fuquay Varina, NC
How would you be able to tell what finish you have on the block.I will be getting the heads redone anyway. And the machine shop I use probally does it that way because they said for about the last year cometics are all they put on anything now. They are what I have on my 408 for my 99SS.
Staging Lane
Joined: Feb 2006
Posts: 80
Likes: 0
From: St. Charles, IL
There is a "tool" that will read the roughness I believe. There have been numerous threads regarding this topic. It seems the Cometics are pretty set in needing to see this finish, otherwise there are some noticable sealing issues.
You said you were using a "copper head gasket" from Flatout. Is the block o-ringed for this style of gasket???
You said you were using a "copper head gasket" from Flatout. Is the block o-ringed for this style of gasket???
On the Dyno the car ran fat. On the 150 shot the gragh started at 12.0 and at 6000 it was 11.2. What Gap would you recommend?
Thread Starter
10 Second Club
iTrader: (6)
Joined: Mar 2007
Posts: 952
Likes: 0
From: Fuquay Varina, NC
There is a "tool" that will read the roughness I believe. There have been numerous threads regarding this topic. It seems the Cometics are pretty set in needing to see this finish, otherwise there are some noticable sealing issues.
You said you were using a "copper head gasket" from Flatout. Is the block o-ringed for this style of gasket???
You said you were using a "copper head gasket" from Flatout. Is the block o-ringed for this style of gasket???
I have the heads off of the engine now I will pull the timing cover off THURs. and take a look. If it is advanced that is too easy to set it back to 0. So bringing the quinch back down to .035 will help prevent the heads from lifting on nitrous even though i will be raising the compression .
Running a quench height of .035 means gasket thickness of .028. That means SCR is gonna be 13:1, which don't really mean **** if your DCR is in check. And the added detonation resistance of low quench height means less head lifting (assuming that the heads are lifting and that it is caused by detonation). You better get your degree wheel and dial indicator out. And lets hope that you don't have to turn it so far back that it causes your other valve timing events to be out of whack. I'll come down and help you if you'll put my clutch in while I'm there.
Joined: Nov 2001
Posts: 10,023
Likes: 6
From: LT1 land...the "409" of the 90s!
Staging Lane
Joined: Feb 2006
Posts: 80
Likes: 0
From: St. Charles, IL
If you are going through head gaskets (they are leaking cylinder pressure)and they are copper and the block is not o-ringed and the cylinder head does not have a receiver groove, I would tend to believe this is your problem. Why are you running copper head gaskets on the motor???
Joined: Nov 2001
Posts: 10,023
Likes: 6
From: LT1 land...the "409" of the 90s!
Or at least that's thw way I'm doing it.
Man three months to go. Times running out and my wallet is alot thinner.
