The best gasket to get is a multi-layer steel (MLS a.k.a. cometic head
gasket). Its the ultimate in durability. Lots of engines' designs are not
engineered to properly utilize an MLS gasket reliably and i'm sure when our 2.2
/ 2.5's were developed, and MLS gasket was not taken into consideration.
Doesn't mean it won't work though. It could be coincidental that the design
will work perfectly fine with it. I've been asking around various lists to see
if anyone has put 10's of thousands of miles on an MLS gasket with a 2.2 / 2.5
but it doesn't seem that anyone has, at least they haven't gotten back to me.
It takes lots of thermal cycles and miles to finally make one fail... such as a
daily driver. IN race applications it'll last seemingly forever. I'm sure
that I'll be one of the first to put such miles on one of these if I can get
this car road-worthy again this spring.
Now, more importantly, the machine work to surface the head and block needs to
be different than what is acceptable for a generic gasket. There are different
smoothnesses that can be machined into the surface and its measured in AU's
or something. I'm fuzzy on that. The MLS gasket requires a smoother surface
to be installed on. Say you were to buy a brand new short block and brand new
head from mopar that has been surfaced installing an MLS gasket in that
setup is not a good idea. The rough surface machined into the head and block
will literally tear the gasket apart in time. The same thing happens to
generic gaskets if installed on too rough of a surface.
Both Ford and Chrysler have been using MLS gaskets extensively now. They say,
that if a head's surface were to become warped, or scratched, etc you need to
REPLACE it, not re-machine it. Its both bogus and true because most machine
shops (especially back yard ones) are not capable of producing the smooth
surface necessary for the MLS gasket to slide around properly on and will
result in gasket failure. But its bogus in that SOME modern shops CAN
re-produce the proper surface with the proper equipment and there's no reason
the head cannot be re-used. That, and you can re-machine it at the back yard
machine shop and use an aftermarket composite gasket without troubles.
How long will it take for a backyard shops' surfacing techniques to cause an
MLS gasket to fail? It could be 5,000 miles could be 50,000. I don't know.
Just a little nasty food for thought.
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