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Gm Head Gaskets

6.2 turbo

6.2 turbo

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Does any one know what a factory 6.5 GM head gasket looks like, especially the fire ring ? I'm looking for a head gasket that will accept a oringed block. Victor Reinz 4021T has the widest fire ring so far,but it is still a wire ,but ss, felpro has a narrow fire ring,with copper wire. Copper head gaskets are not cheap and with my luck will probably leak water.:mad2:
 
I have a set of factory head gaskets, what would you like? I can take a picture, or I can measure the fire ring width for you.

Here is a basic read for you on O-ringing engines and head gasket selection, the advice there is bang on.

A properly installed MLS head gasket will hold a TON of pressure.
 
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A picture would give me a pretty good idea, also what is the fire ring width , fire ring design,is it wire overlapped in stainless? I have mixed feelings on mls gaskets,my head and deck are not true enough, but it seems cometics could be better in design, seems they should have more clamping force at the fire ring instead of the same over the entire head.
 
By far the Victor Reinz has the largest fire ring. I think I like their 6.5 gasket better than the Felpro. I certainly like their 6.2 gasket better than the Felpro 6.2 gasket. I won't use a Felpro 6.2 gasket on anything any more. The current Victor gasket looks almost identical to the Felpro gasket that was used in the 80's (black with orange printed sealing rings).

No one else that I know of makes a good gasket. Detroit gasket made one, but they were so horrible that it's hard for anyone else to try one again.

ROL made their own gasket, but currently just box Felpro in their own (pretty dang lame).

Where are your gaskets failing?

Mine always fail on the end coolant ports, even on the stupid re-inforced ones. That's been 100% Felpro's though. I was going to try the Victor on the Race 6.5, but I'm just going to give up and pull the engine and have the block and heads surfaced smooth as a baby's ass and install the cometic's.

Didn't you say you had a problem with the Cometics too?

Head studs will help, but they leak coolant, oh do they leak, it's a hate hate relationship.
 
Oh, and to answer YOUR question. The Factory 6.5TD gasket IS a Felpro gasket, always has been.
 
I was afraid of that. The gaskets I have in now are the Victor Reinz with the orange sealing rings I'm sure it blew at the ends like all my others did ,my Cometics even leaked there. I installing my studs with grease and hand tightend they leaked like a sieve, next time I used permatex # 2 and tightend them as tight as I could with an allen wrench no leaks,but we could hardly get them back out,I'm using orange silicone on the threads now ,no leaks either. My deck and heads might be some what to blame on the Cometics. I'm thinking of putting a dowel pin exactly at the spot were the gaskets blow, to hold the fire ring, I blow all for corners at the same spot. If I were to oring the block with ss wire and dead center on the 6.5 Victor Reinz head gasket fire ring it might work? I also thought of copper orings and Cometics.
 
6.2 turbo said:
blew at the ends like all my others did ,my Cometics even leaked there.
Click to expand...

How did the Cometics leak at the end port, since there is only one coolant port on those (not ambidextrous).

Were you getting compression in the cooling system?
Did the physical fire ring move?

Finally, did you pull a compression test before pulling the head? That'll tell you where, before removing the head to carefully examine the cause.

I don't see any reason to fire o-ring the block or the heads at this point. The rings don't seem to be moving, the problem lies in the end ports. Maybe o-ring the bean shaped coolant port. I've been thinking there needs to be a thinned walled sleeve made for this port to seal it.

J
 
Liquid Teflon© and snug is all the head studs need to be (with very clean threads).

For the gaskets to seal properly you need a specific RA, I believe 60 RA or better is usually the requirement.

As for using O-rings, you will find that the manufacturers of the head gaskets will know more about use of them with their gaskets than anyone else. If I remember correctly, Cometic says to not use O-rings with their MLS head gaskets.

Usually a head gasket is used as a gauge. It is the one thing that is allowed to blow if undesirable conditions exist inside the cylinder. Rather than cracking pistons, bending rods, breaking pins or cranks, the head gaskets will blow, which is a much easier, cost effective part to replace. You then find out what caused the gasket to blow, such as too hot of combustion temperatures or too advanced timing, which will cause a massive spike in cylinder pressures, and a pressure wave that will break parts. What happens when racers break their forged crankshafts, they do not make them stronger and more bulky, they find out WHY they are breaking, and fix it.
 
Cometic wants 50RA or better.

The method mentioned slightly above this post on the heads studs will enable you a crankcase filled with glycol.

The fastener to thread bore size is tight on these engine, very tight, allowing little if any of the sealant to stay on the threads where it's needed. it simply is squeezed out the top.

The needed sealant needs to be both thin and hard-setting. None of this "soft set" crap. Schoolcraft used a loc-tite, which seems logical, but I have no feedback to support it's sealing ability long-term.

I agree with the use of RTV on the threads, seems to be the best sealing so far.

If repeat failures of the end port occur, the most likely thing is that the block and head surface is lacking in this area (slightly eroded from the past failures), so it may not hold a gasket.
 
The Cometic looked like they were leaking at all 4 ends into the water ports,even though the front port is blocked the head port is still open,on the Victor Reinz the fire ring was pushed about 1/4 inch towards the water ports. I don't want my head gaskets for a fuse,I now what is making them blow,the fact still remains the gaskets are no good,and horribly designed. I 'm happy with using silcone on the threads and tightening the studs past hand tight.
 
chevydiesel said:
The needed sealant needs to be both thin and hard-setting. None of this "soft set" crap. Schoolcraft used a loc-tite, which seems logical, but I have no feedback to support it's sealing ability long-term.
Click to expand...

Do you know if Schoolcraft loctite's the studs, screws them in & then straight-away torques down the head, so there's some approximation of normal strain on the stud as the loctite sets up?

I've worked around an engine builder that was a firm believer that the stud threads/block threads needed to be under their normal strain load while the loctite cures.

Part of his reasoning was for better sealing threads that go into the water jacket. The other reason was it helped ensure the studs set up as perpendicular to the block deck & as parallel to one another as possible - sometimes making pulling a head (w/ limited clearance in the bolt holes) easier.
 
You'd want the lock tite to only set up after you've stretched the studs to torque, so under a load. I don't know if that'd really help for removal though.

But yes, the key is install all the studs, then get the head installed and everything else torque on before the time limit where the chemical sets up.
 
I have to remove the studs every time I pull the heads,not enough room, I would not want them lock tited in. I think ARP recommends teflon paste.
 
In chassis, won't work that well for future service.

ARP sells a teflon enriched (chunky) paste for head studs. Guess what? Leaks too.

J
 
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