Since we are talking about one of my favorite topics, I just have to jump in
here.
In this modern day of Multi Layered Steel gaskets for many popular engines
I'm wondering why we would even consider using a flat copper head gasket.
(unless we are using an engine for which a MLS gasket has not been designed.
Except in a very highly boosted engine, most factory MLS gaskets of at least
3 layers will seal both combustion and fluids on most production based
naturally aspirated engines of very high power levels and cylinder
pressures. I have looked at the 3 layer Cometic design, and while the
design is not perfect, it should (and does) work well on many applications.
All sealing is or should be accomplished with "unit load" so the embossment
on the MLS does what a wire ring reinforced armor (fire ring) of a composite
gasket plus seals water and oil passages with extremely good unit load.
There are weakness' though, in that the surface flatness, and finish must be
exceptionally good with no waviness. Many machine shops are now capable of
providing the appropriate finish and flatness. If any shop tells you it
isn't important, do not give them your heads and block. Fel Pro is also
making many MLS gaskets for production as well as aftermarket, and of course
has the background to do a downtown job.
I think that the only guys that should be using copper gaskets are top fuel
racers that pull the heads after each pass. Even then, a properly designed
MLS gasket might do the job for them, but the problem is development time
and the system they now have seems adequate.
Many highly boosted engines use hollow, high pressure gas filled metallic
"O" rings to seal combustion gasses and rubber "O" rings to seal fluids at
the head joint. This is costly, (for me around $150 to pull the head), but
it seals almost perfectly. almost.......Same issues as MLS with surface
finish.
If you have to use a copper gasket, the use of a thread to create unit load,
along with something like a teflon paste sounds like a good idea unless you
machine a counterbore and use rubber "O" rings like in the metal to metal
joint. With elastomer "O" rings or MLS, I would think that around a hundred
pounds of coolant jacket water pressure would not be a problem at all, but
to know that would require good data and I don't think any of us knows
exactly what the water pressure is at the head deck.
Rick Byrnes
Oh, and yes Goodman, I'm working on something.
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