LTxDave

383 LT4, AFR 210's, 9:1 compression, 14 PSI boost, alcohol injection. What would you use? Right now, I'm leaning toward Fel Pro MLS gaskets if they make an LTx application.

Fatt Vette

MLS is a great way to go, but make sure your machine shop FULLY understands the surface finish criteria necessary when decking your block and/or resurfacing your heads.

The rivets that hold the gasket together also interfer with the AFR head deck and will not allow them to seat completely, so make sure to cut reliefs in the heads.

SloRvette

All you need to do is remove the rivets. The dowels in the block will locate the gasket and keep the layers lined up.

I just bought a set of the Fel Pro MLS's. Been using the Cometics for years now. The coating on the Fel Pro's are actually tacky. Just looking at them out of the package I like them. They will pick up dust and dirt so be careful in handling them.

With the Cometics I've always used a sealer (spray copper) on them contary to what Cometic recommends and have never had any sealing issues with them. The sealer makes up for minor surface irregularities in the machine work. Without the sealer the surface needs to be smooth almost to the point that you can't feel scratches with a finger nail.

dr.juice

Well....I've been using Cometics and no complain. The last time I rebuilded the engine, they sent me a wrong set of gasket. I did use the old one and no problemo...600+rwhp with boost and juice and the old Cometics did the job.

mn_vette

Cometic is the way to go if you have a freshly surfaced deck and head.

If you are replacing a blown head gasket Felpro makes a performance head gasket that has been holding up for me just fine.

kverges

Also, I recommend re-torquing after the first warm-up. Huge PITA, but I have had the same old Fel-Pro permatorque blues on an 11psi Vortech S/C car for over 3 years with no issues

LTxDave

Some local folks seem to have trouble with the Cometics leaking. I was planning to stay away from them if possible. I do have studs and plan to retorque after breaking the engine in. Thanks for all the info.

ztrips

I have Cometics and a leak... I had the combustion chambers coated and I think that is my problem. No compression leak, but I have an oil leak that starts at the oil drainback holes and goes to the rear of the motor. No fun.

LTxDave

Yeah, that is the type of leak that I have been warned about.

tjwong

Your block and head surfaces has to be cut on a CBN machine rather than an old style surface grinder. If you have or had it cut on a old machine I wouldn't bother attempting to use the MLS gaskets. I had a engine prepped on a old style machine and the damn thing leaked, basically it will seep oil. I am using a set of LT4 GM composite gasket with studs making 12 to 14 PSI and have not experienced any issues. They key to making this work is to avoid any detonation, if you do that with a good tune a standard composite gasket or even a Fel-Pro 1074 will work fine as long as studs are used. If you attempt to use the MLS, and in the case of the LTx engines it will have to be either Mr Gasket or Cometic, and be advised that Cometic makes Mr Gaskets MLS gaskets in one flavor that being said they are made as a .040 thick gasket, and in both cases you will need to remove the rivets for clearance or notch the heads. I suggest removing the rivets and coating them with copper coat.

AKS Racing

I have used the Cometics with copper coating for many years in boosted applications with no issues. Even turning the boost up has not caused an issue, to date. (knocking on wood)

But, I think one thing that is helping is that the block and heads were prepared for MLS type of gasket, And the AFR heads have the extra thick deck, which helps keep them seated.

Aaron

ztrips

So is there a fix for this, other than pulling the heads off and using another gasket?

Thanks

97AGGIE

Always used Cometic w/a copper coating w/no probs. Almost 13:1 and nitrous here!