... and if the block is decked and not perfect, end-to-end & side-to-side,
things will get even more complicated.
I shoot for .005 on composition and .002 - .0025 on steel gaskets.
Glen
-----Original Message-----
From: Mordy Dunst via Fot <fot at autox.team.net>
Cc: fot <fot at autox.team.net>
Sent: Tue, Aug 1, 2017 8:53 pm
Subject: Re: [Fot] Figure 8 gasket thickness
The entire fig of eight gasket concept is so wrong. Who would have designed
such an arcane system. I measure each liner independently UNDER LOAD and they
do compress - similar to rod bolt stretch. Any rate you measure the sleeve base
to top and compare that to the measurement of the internal block sleeve perch
to the deck. Add .005" to that block measurement subtract the sleeve
measurement. That's the thickness for the base gasket for that sleeve. The
sleeve next door might be different. It is not an issue for stock oem type
compressible gaskets but critical for solid type metal gaskets. Sleeves
compress .001" @ 100 ft lbs torque on them. If you email me separately I can
share photo. MDunst Headgasket.com 626.358.1616 Fax 626.628.3777 Triple R
Munitions, Inc 626.201.9471 T FFL 6,7 SOT 2On Tuesday, August 1, 2017, Jack
Wheeler via Fot <fot at autox.team.net> wrote:Hi Tim. I rebuilt the engine in
my street TR-3 (10:1 compression, mild cam, etc.) a couple of years ago. I
used the steel figure 8 gaskets, and the liners were a new set of 87MM from
Moss (so were the gaskets). After break in, I noticed it still using a small
amount of oil. I couldn't see any leaks, and with new pistons/liners I can't
imagine I was getting blow-by past the rings. I ran a test on the coolant and
found a small amount of combustion gas in the coolant. At the time of
assembly, I checked the amount that the liners were "standing proud" of the
block, and it was marginally within spec, maybe a little below. I would have
liked to see it up around .004 - .005. Instead, I was getting .002 - .003,
which I concluded accounted for the missing oil (i.e. oil leaking past the head
gasket and into the combustion chamber).So, I did an 'in chassis' rebuild and
replaced the figure 8 gaskets with some old copper ones that I happened to have
around. I have a lot of figure 8 gaskets (left over from my racing days), and
I checked all of them (steel and copper). On average, I was finding the same
thicknesses being reported in these messages, with the copper ones measuring
about .002 thicker than the steel ones. I put it back together with copper
gaskets, and that solved the problem. It passed the coolant test, and hasn't
used a drop of oil since I changed to them 2 years ago.Hope this is helpful.
Good luck.Jack WheelerOn Tuesday, August 1, 2017, 12:57:37 PM EDT,
timmmurphh--- via Fot <fot at autox.team.net> wrote:Thanks for the responses to
my recent post regarding the thickness of the figure 8 gaskets. I?ve done a
little more ?digging? and these are my results.All of the steel ones I have of
have gotten measure 0.015+. I recently ordered some non-copper ones from
British Parts Northwest and they are aluminum and also measure 0.015+. These
are the first aluminum ones I?ve seen.All the copper ones I have, including
some used ones, measure 0.020+.I contacted Moss US and asked about their copper
ones and any problems. They only had one report of water leaking, back in
2014. I was told that maybe the copper 0.020 ones were supposed to compress. I
hammered some copper ones to 0.015 and they are twice as wide as the original
and would not fit between the liner and the block bore. Additionally, I don?t
think there is enough force to compress them.The Moss ones are from Moss UK and
are now specified at 0.018 by BPNW. The BPNW part number is the same as the
Moss UK part number. I contacted Moss UK by email but never got a response.I
also recently ordered a Payen lower engine gasket set and the figure 8 gaskets
in it are steel and measure the 0.015+, as all of the other steel ones.The one
engine builder that I know who uses the 0.020 copper gaskets typically uses
them on blocks that are decked with the liner seats cut to allow the 0.003 to
0.005 stick out as specified by the Triumph TR4 Workshop Manual, Pg. 1?121.I am
interested in anybody who is using the copper gaskets. Please post how you are
getting the proper stick out.For myself, I will continue to use the steel
figure 8 gaskets. I would also be interested in anyone using the aluminum
figure 8?s. Any problems? What did you get for stick out when assembled and
the liners clamped in place? Personally, I don?t think I want to experiment
with these.Tim Murphy1961 TR4 #317 (It really is a 1961 with an early
Commission Number CT511) _______________________________________________fot at
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