Mike:
Before tearing anything down check the cam timing. During assembly
it is really easy to get one tooth off. This leads to a really doggy
engine, with no other symptoms.
good luck.
Kelvin.
> -----Original Message-----
> From: Matt Milkevitch [mailto:milkm@mail.vt.edu]
> Sent: Wednesday, March 10, 1999 6:42 PM
> To: mgs@autox.team.net
> Subject: Compression test- - -opinions needed (long)
>
>
> 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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