Headgaskets (Info from locked thread on big boards)

[UptownSport]

Discussion of removing HG shim for a 'free' increase in compression.
Note, there are several different manufactuers and also different versions.
Currently, it appears Chrysler is selling the Fel-Pro gasket. ~$35 from
RockAuto. Also note, no one credible has reported issues w/ this mod.
several voice philosophical concerns.

Random idea popped in my head while tooling along in
traffic... why not remove the middle mls headgasket layer to up the
compression insted of decking the head? The 2 outter layers are 0.010"
and the middle is 0.020". I believe the outter layers are flat indicating that
they "might" seal without the middle layer.

Yes, this has been done many times. And yes, it will
work if the head and block surfaces are flat and prepped. I made up a 5
layer, ~0.075" thick gasket once to reduce compression. It stayed intact
until the engine killed itself from other reasons.

I ran my 2.0 with the center layer of the headgasket
removed and the head milled .030 for many thousends of miles with
never a headgasket related problem. Removing the center layer is really
very common.

Shaved head + missing layer here too. About a year w/o
problems.

yep, been there done that.
0.040" off of a head and yanked the middle layer.
169 whp and 143 ft-lbs with a stock bottom end 2.0

Discussion excluded HP capabilities of certain engines, and objections
due to med not being in 'good form.'

Agreed. That said, cylinder pressure is cylinder
pressure. It's safe to assume that 200+ whp cars have a fair bit, and no-
one I know with a removed layer (it's been done by MANY, MANY fast
people) has seen a resulting gasket failure. I'd in fact argue that for many
people here, it's more likely that an installation error when installing the
DOHC pistons and rods could lead to failure.

Yeah, kids these days.

I have done the headgasket layer trick too. I believe it was in Mopar
Action Magazine many moons ago.

Ok, so to sum it all up, by removing the middle
gasket in the MLS HG and shaving the head (lets say .030), an otherwise
stock internals 2.0L can make AROUND 150whp?

If so, great. I know what I'll be doing when I'm ready to change the HG. Thanks for the info everyone.

Three other question I have about the headgasket while we are on the
subject.....

1) I have noticed that the holes in the gasket for coolant to pass through
vary in diameter from one side of the gasket to the other. Is the reason
for this to keep coolant flow through the engine even to keep it cooling
evenly?



2) By "the middle layer", do you mean the silver gasket sandwiched
inbetween the 2 sealing gaskets and the other gasket that appears to be
thinner? (Mine only has 4 layers to it)

3) Do you just drill the rivets and pull out this "middle layer"?

#1=Correct

#2 Do all the layers look to be about the same thickness? The middle
layer on the 3 layer gasket looks alot thicker and measures thicker as
well. Numbers are above somewhere...

#3 I'd assume so. Haven't done it yet.

There is one layer in the 4 layer gasket that seems thicker and alot more rigid. That would be the layer to remove I assume and then I'll just get the ARP head studs and put a couple extra pounds on them to make sure they seal tightly.

There is one layer in the 4 layer gasket that seems thicker and alot more rigid. That would be the layer to remove I assume and then I'll just get the ARP head studs and put a couple extra pounds on them to make sure they seal tightly.

Geez people... READ... its the thickest stiff middle layer


anyway as for mike, you dont need to spend the money on ARP hardware

i ran my old head with the middle layer removed and it was 100% fine
with the factory head bolts
i even used the same bolts when i swapped to the magnum head that was
decked .035 and it was fine
just make sure the threads arent stretched , if your that paranoid just get
new factory stuff

So the coolant holes are to force the coolant (which appears to enter on the pass end of the block) circulate to the drv's end (where the holes are large), then return thru the head, exiting the Pass end of the head, where it exits thru the water neck (or t-stat hsg)?



I guess if it's working on so many vehicles, then it's not a necessary part of the design.

Here's my measurements: (Fel-Pro)



Is MoPar the same/similar? (center layer appears to be at least two peice, but glued together)
FYI stock engine (MP PCM) on premium

I had a 98 sohc with the missing layer. It always ran fine but after I disassembled it I found the head to be really clean in some spots... Tight clearances. Mustang dyno's are kinda "tune-able" too.

Several questions and more discussion about capabilities of SOHC engine,
concerns about longetivity of Fiat engine w/ increased compression,
ommited.

No, the 420A used in the Talon/Sebring/Avenger/Eclipse did not have the MLS gasket from the
beginning. They would leak oil also, as they had the composite gasket
until probably late in the 1998 calendar year.

The Mopar MLS head gasket has 4 layers specifically so that it is
essentially the same compressed thickness as the previously used
composite gasket. This was done so that the MLS gasket could be a direct
replacement for the composite. If it were thinner, there could be an effect
on emissions which would not be legal. I would be leery of removing the
middle silver layer, because it has the specifically engineered and tested
coolant restrictor holes in it. The "extra" layer inside the gasket could be
removed easily for a small compression bump, though.

Just installed the Fel-Pro.
There are four layers.
.010 top
.013 Shim coated one side only; HAS Coolant Restrictor Holes (pulled)
.016 two piece; HAS Coolant Restrictor Holes

It was difficult to separate the shim from the lower two piece.
I don't think I'd get the two piece apart without bending something.
The gasket was very sloppy on the deck. The dowel holes must've been in the shim.

Edit:
I'd get screws, rivets, etc to replace the ones drilled.
That will keep the gasket fire rings from falling off one another.
The block dowels will no longer do this

I have ~35k on this one. It has > 11:1 CR.
My brother also removed it on an engine w/ similar CR.
I pulled multiple shims from HG's when I was swapping
heads around. None of them showed any signs of failure.
The part you remove is a shim, (reread Greg's post above)
it's designed to fill space, thats all.
I do not run fans and periodically the engine will get very hot.
This does work and it is reliable.

#1 is HOW, or the method on how you get CR. The
most important is the shape of the combustion chamber.
The quench distance is a main focus here. Removing
the shim reduces this; all deadspace. Read here:

http://www.popularhotrodding.com/tech/0 ... ocity.html

Note; you could also do this by decking the block, or having
your crank reground w/ a slight stroke offset. Obviously this
is the most inexpensive and is also reverseable.

There was another post w/ info on pulling shims on the new
HG, I'll see if I can find the info.

Here they are, dunno where the actual posts are.
Basics are the new HG has to be centered if you remove
the shim, the shim is what does the centering ...

Facts:
Exactly 50k on this HG. I've overheated it several times;
don't have cooling fans, chimes went off. Milled head tons
(you can read remarks on how bad that is, too)
My brother has the same setup (removed shim) no issues.
I'm sure Cometic (they didn't have said HG in stock when I called
last time these false concerns were raised) is fine @ (IIRC) $80 a
'pop.'

Simply, don't be mislead. The person raising these concerns continuously
makes claims he won't (can't) support.

[UptownSport]

Update, seems Fel-Pro changes headgasket designs somewhat frequently, it's now ~.014"
Went from black to Blue, note both shims below are coated; one clear, one black.