Welcome aboard. It was nice to see a message resembling what the list
can do.
Later,
Carl F. Musson (musson@arts.usf.edu)
'58 TR3A TS25264L www.arts.usf.edu/~musson/triumph/
Tampa, Florida (USA)
-----Original Message-----
From: ghaslem@juno.com [SMTP:ghaslem@juno.com]
Sent: Sunday, October 12, 1997 3:01 PM
To: triumphs@autox.team.net
Subject: Re: Compression test
Let me start by introducing myself. My name is Glenn,
and I live
in San Antonio Texas. I own several TR7's, one for 8 years that
is my
daily driver, and a couple others which I'm in the process of
fixing up.
I've been a lover of LBCs ever since I was a kid, and my oldest
brother
bought a band new 1967 MG. I just signed up onto the Triumph
list last
week, apparently not the best weekend to start. But overall I'm
enjoying
hearing some of the advice and tech talk and am glad I've signed
on. I
am a bit jealous about the good weather all over the country.
Here in
south Texas it has been raining for a steady week.
I agree with the comment that the actual numbers on a
compression
test are not as critical as the differences between the
readings. As you
can tell from the responses there is no absolute number which
one call
declare the engine good or bad. There is many different factors
that can
make the overall reading all high or all low, from barometric
pressure,
humidity, timing, temperature(both outdoor and engine). When I
lived in
Wyoming, at 7000 ft altitude, I was lucky to get readings above
110. Now
that I'm down closer to sea level my pressure readings are
considerably
higher. The main purpose of a compression test is to find a
cylinder(or
cylinders) with excessive wear. Normally one can consider the
cylinder
with the highest reading to be the most efficient cylinder. The
cylinder
with the lowest reading is the least efficient. If the
difference
between the two cylinders is greater then 15%, then there is a
problem to
investigate. If two cylinders side-by-side are low, that is a
good
indication of a blown head gasket. If one cylinder is low, then
a squirt
of oil, as describe by another reader will lead you to the
problem. If
the compression of the low cylinder increases with the squirt
of oil,
then the rings are leaking, if the readings stay low, then a
leaky valve.
The concept of pressurizing the cylinder sounds
interesting.
I'll have to check that out. My father used to pressurize the
cylinders
in the fashion described to change to valve seals without
removing the
head (the pressure keeps the valves from falling in).
I've seen a lot of references to history books and
commission
numbers this weekend. One thing I've learned over the past
years is to
not put much faith into BLC record keeping. I have a TR7 which
the
title say 1976, the emission sticker says 1976, and the exhaust
design is
typical of 1976, but "the books" indicate that the commission
number is
1977 model. I've also know of a 69 TR6 which came from the
factory with
TR5 door panels, always a problem in concourse competition since
it
doesn't look original, and several cars with commission numbers
or
paint codes that don't exist according to "the books".
Again, I look forward to hearing all of your experiences
and tech
tips. (and No, I'm not a doctor, I am one of the common folk
who can
barley afford to keep my car on the road, and love every minute
of it).
Glenn Haslem
2 1976 TR7, 1979 TR7
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