samluke

O ringed head but no ring, ie just the reciever groove. Widefirering gasket. Stock studs 3yrs no problem.

Previously I was lucky to get 3 months and that was with raceware studs the works, and never did get it to hold up.

In my opinion an "O" ringed head is cheap. There are only benefits and no detriment, and its always a good sales point when the time comes. I always recommend O ringing, whats to lose.

Van

As you can see, there are many schools of thought, and many people using different techniques succesfully.

Personally, I have a copper head gasket and stainless steel o-rings in the head.

Whichever route you take, you have to allow for material deformation and make sure something is "soft" and somethine is "hard" (otherwise you can't control the defformation).

The stock head gasket (and WFR) has a thin steel piece of sheet metal that is crimped over the edge of the fiberous gasket, and it's the deformation of this piece of metal, between the aluminum block and head, that seals the combustion chamber.

If you make a groove in the head (or block) for this piece of metal to deform into, then you can make a seal with more area, and it will be better.

Likewise, if you o-ring the head or block, and machine a reciprical groove on the other part, then you crimp the head gasket into an "interlock", which is also good.

I think it really comes down to what your machine shop is comfortable with doing -- this is a job that has to be done very precicely and is easy to **** up.

I've had good luck with the diagram below -- my machine shop was able to accurately make the grooves in the head, and by doing some material calculations, I was able to figure out how much of the copper would deform and what the head torque should be.

mwc951

And a good pic says it all!

mj951

samluck, whats the reason for leaving out the o-ring?
clouddomino, DLS only has the head off. is there a difference in performance between o-ring in the head vs. block?
968turbos, is it true that mls recommends no o-rings with there head gaskets?
has anyone installed an mls without resurfacing head/block/both?
not trying to kill a dead horse, just hoping to summerize.

mj951

van,
nice explanation, very informative...thanks for the diagram.

samluke

There are so many opinions on what works best. And what works best depends on state of tune, boost level etc etc.

If you leave the ring out you maintain the maximum clamp force against the cylinder walll which is where the gasket starts to fail. The gasket deforms into the groove which stabilizes the firering.

I think its safe to say, and generally well proven that something is better than nothing.

Porschefile

MLS headgaskets are typically made of steel (other than copper I can't think of any that aren't) and don't deform or squish nearly as much as a stock "paper" type gasket will. Using an o-ring with an MLS gasket can normally lead to sealing problems. As Duke said, if using an MLS headgasket, no o-rings, deck the head and block, and preferrably upgrade to ARP, Raceware, or some other high grade aftermarket non-stretch (well, less likely to stretch that is) head studs. MLS gaskets are just less forgiving with imperfections.

Mj951, MLS stands for multi-layer steel gasket. It's just a type, not a brand. AFAIK, Cometic is the only one that makes an MLS gasket for these motors. Most engines over time, and especially with overheating or blown headgaskets will tend to warp the head and block mating surfaces. Inline engines are even more prone to this. As a result, with an MLS gasket that has less squish and cannot deform around imperfections, warped surfaces will cause sealing problems. That is just a fact, and probably the number one reason why some people have sealing issues with them. Most people are too lazy to pull the motor and have the block decked, and they think decking the head is enough. It's usually not.

For big boost, higher rpm, or big hp cars, an MLS headgasket and arp, raceware or other aftermarket studs are the only way to go IMO (at least to do it right). Many people seem to be getting away with the widefire just fine at some decently increased power levels such as 400+whp but at that point any paper gasket is going to be stressed and much less likely to keep a seal as opposed to a properly used MLS gasket.

Van

You actually mean less "creep" -- which is undesirable stretching over time. The stretch is a necessary factor for proper torquing. We covered that in another thread.

Charlie944

O-ringed head here with a WFHG. I was wanting to run a Cometic, but feared leaks because I did not have machining done to the block. With the O-rings you can easily take them out and run Cometic MLS headgasket if you so choose later once the proper prep work has been completed. I do track the car and run 16psi with the current turbo and MAP setup and have zero problems.

Inexpensive work for the benefits you gain.

RajDatta

That is correct.
Raj

Ski

If the block is out, why not o-ring the block...sorry for the little white thing and Raj got it right, no o-ring with MLS unless you can get the o-ring PERFECTLY centered in the dimple...according to Neil.

thoriums

i'm not a big fan of o-ring..

Laust Pedersen

My engine: Block never surfaced, old type Cometic MLS gasket, which has been re-used, O-ringed head (SS O-ring not centered at the HG dimple), 25 psi of boost and perfect oil, coolant and combustion seal.

As to the compressibility of MLS gaskets, don’t forget that the Cometic gasket has a thin layer of Viton rubber on each side. That headgasket also has a middle layer that is slightly thicker where it mates with the cylinders, hence higher clamping force there.

There is a substantive difference between saying: “We do not recommend using an O-ringed head” and saying: “We recommend that you do not run an O-ringed head”. As a Cometic technician also told me: “We do not recommend re-using the gasket, but many people have done it with success.”

Btw, an O-ringed block with an MLS gasket will reduce (eliminate?) the rocking motion of the cylinder.

Laust

reno808

i dont think it would be wise to REUSE the HEAD GASKET.

95ONE

Lets not confuse "lesser head gasket" with , In correct tuning. For those with chronic head gasket problems, what timing were you running? Chips?