The gasket is NOT too thin. The finish on the heads and block are not slick enough for the Cometics to seal. The stock finish is too rough and the gasket is so hard it will not squish down in the grooves to seal them and that leaves little valleys for the fluid/compression to get out of.
To make them work ya need a Ra of 50 or finer and that's starting to look like a mirror at that Ra.

 

I do about 3 sets a week of Cometics between Heads/cam swaps on LS1s or complete engine buildups, mostly with ARP studs, but occasionally with stock TTY headbolts. Never leaked a drop of water on ANY of them except for on one of my Turbo Mustang's after running 20psi of boost (15yo stock deck surface). They leaked a few drops for a day or so and never leaked again while I owned it. I would say that I probably lifted the head from detonating before I blame the gaskets.

Cometics work fine with Copper spray and correct torquing procedures. I don't like using the stock TTY head bolts, but never did have problems with them either. Most guys do not need the MLS gaskets other than for the different thicknesses available from Cometic. Stock GM gaskets "function" equally well as a gasket, but do not offer tighter quench that some people are after. Stock quench is .055"-.060" when the engine is warm. I like quench to be .035"-.040" on all-out N/A setups.

I still stand by my statement that the head bolts do not have sufficient torque by incorrect installation procedure. I would take them off, clean them with carb cleaner/water then spray some copper spray sealant over both sides and reinstall with ARP hardware.

 

I have used them a time or too also.
I still stand by my statement that the finish isn't correct as documented on their web site.
AFAIK ya aren't supposed to use glue or anything else to seal them.
I have run them with 26# of boost with no problems as the surface finish was correct.
I would suspect they know what works with their product more than an engine builder. It pays to recommended procedure when installing anything on an engine.
This post is an example of just buying something and installing without following the recommended procedure.
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Why does Cometic recommend MLS gaskets to be installed dry?
Cometic Multi-Layer Steel (MLS) head gaskets go on dry because they are coated with a sealant. Each MLS head gasket is coated with a .001" thick viton rubber that is bonded to the outer stainless steel layers. Adding an additional sealer can hinder the performance of an MLS head gasket.


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.

 

Recommended procedure would be to R+R the engine, dismantle the engine and send it to a machine shop to have the deck resurfaced to the correct RA. Who is going to do that just to run a certain brand of gasket though? I would think the heads (if machined with a carbide bit at the correct feedrate for a final cut) have a sufficient finish on them.

Thinking about it, most of the engines I build are built using new virgin cores for heads and block. I could probably get by without using copper spray on those setups, but will continue to do so because of my good results thus far. Copper spray is cheap insurance and it works.

If you ever use stock head bolts with cometics you will see what I am meaning by the torquing procedure. The center 6 bolts will not be the same torque as the outer 4 unless the 22lb ft is retorqued at least twice.

 

The PROPER procedure is to NOT use Cometics gaskets on a replacement basis with a stock finish.
If ya have a surface roughness tester(about $3500.00) ya could test an engine when it comes back from the machine shop,before rebuild. I have one and test the bores for right finish for the rings going into that engine and head surface if using Cometics. All MLS gaskets have a certain finish and all Total Seal rings have a certain finish so if ya want to be up to speed ya need to utilize the latest tech.
The spects on these things aren't put out to be ignored.
If ya ever had a set of Total Seal Stainless rings NOT seat and ya got to pull a customers engine back down and fix it on your nickel it is worth paying attention to the INSTRUCTIONS

If Cometics thought anything rougher than 50Ra would work they wouldn't recommend that the surface be 50 or less.

Another example of not reading the instructions if all else fails.

 

They have .001 layer of Viton on them and that won't seal a very rough surface, but it obviously works with a very fine RA. For extra water sealing assurance and/or a questionable RA, some of the turbo guys use Hylomar spray, and I think copper spray has a similar element in it also. Don't know why a guy would choose these gaskets for a R&R, but they are reusable and will probably seal up if he cleans them, sprays them, and gets some ARP bolts torqued down correctly. If not, he's only out the cost of the spray and new gaskets cause he needs new bolts anyway.

 

To start with I don't use TTY bolts. If ya got to buy bolts then why not get some ARP bolts that are reusable.

Torque(clamping force) is torque. If the TTY bolts will torque to Cometics spect they should work fine.

This is with the required 50Ra finish or finner.

Retorqueing is ALWAYS a good idea. I will go through it 2-3 times on the stand. If left over night everything will settle and ya can retorque on the stand. Another thing it has to be done right. Ya have to back off 1/2 turn then retorque or the torque + the friction that is allready there will cause your wrench to click before the torque is reached. Mark them and try it. Don't know how ya would do this with TTY bolts.They are supposed to be no good after the first time.

Most gaskets today do not require a retorque,but if putting 30# of boost on it ya need every little advantage.

 

Since this has become a good gasket/sealant/torque discussion, What would you all reccomend for me?

I'm doing my engine work as soon as my car is repaired, and I still need to get some gaskets and bolts. I know to use the ARP's but i dont know about gasket selection. I've had the heads milled to a fine RA, but the block is still going to be stock. What would be the best way to ensure that i get an adequate seal and not leak any compression for the life of the car?

 

Fel Pro

 

With a NA pump gas motor stock MLS gaskets and ARP studs work great for me.

 

That's great.
They are not needed on a N/A engine.

 

I would bet on your tty bolts not being strong enough, I would never use them on any type of performance build. The cometics work perfectly when the surface finish is correct and you are using quality hardware. 50ra is pretty rough and will easily catch your fingernail, I always go for between 10-15ra with MLS gaskets which is not hard to accomplish with a PCD puck in your surfacer. The stock ra is typically about 17-25 which should seal any MLS just fine if you install correctly,

 

Well I got the car put back together. used fel pro gaskets and everything works fine. thank you to all that gave advice!!
Chris

 

Good deal.

 

I agree.