Fellow Listers,
Approximately 1 year ago, I completed a full rebuild on
of the engine in my '74 BGT. I completely redid everything, to
include 8.7:1 pistons, mild camshaft (Piper BP 270), unleaded
conversion, and so forth. In addition, I also redid my SU HIF4
carbs, replacing a Weber I had previously used. Also, I am running a
cannon header, Lucas 45D4 (Eurospec), and Peco exhaust.
My problem since completion has been lack of power.
Given my modifications, I was looking for an engine that would pull
well, but it remains something of a dog. Granted, what I'm saying is
very subjective...and I was reminded by a friend that these cars
weren't all that fast to begin with. Sensing some type of internal
engine problem, I took it to a local MG shop and had them check it.
They performed a leak down test, and said that I was losing
compression badly, and that they could hear the air leaking through
the oil dipstick hole. This indicated to them that the rings weren't
holding up. In addition, a compression test indicated that all
figures were hovering around the 130 psi mark.
Since that time, I've done a few adjustments (mixture,
timing etc) and have seen some small improvements. I also performed
another compression test giving the following figures:
Cyl 1 = 140
Cyl 2 = 135
Cyl 3 = 145
Cyl 4 = 141
Precision here is relatively good, and the difference
in these figures and earlier ones probably can be attributed to
difference in compression testers. One more note: oil consumption
is about nil, and oil pressure is very good (45 at idle, around 70-75
at 60 mph).
My question to the group: opinions on these
figures/data?? Does anyone have a "ballpark" idea on the ideal
compression of an MGB 18V engine with 8.7:1 pistons?? Right now, I'm
contemplating a teardown and putting new rings on, and would like to
get the collective wisdom of the group.
Thanks for any advice,
Matt Milkevitch
'74 BGT
Matthew Milkevitch
Graduate Student, Ph.D. Candidate
Dr. Karen J. Brewer(Chem), Advisor
Dr. Brenda W. Shirley(Biol), Co-Advisor
Va. Tech
Blacksburg, VA 24061
(540) 231-4708
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