On Mon, 22 Mar 1999, George Hahn wrote:
> What is typical compression (lbs) on an unmodified 1991cc TR3A engine?
The figure quoted in the original "Service Instruction Manual" (so
probably for TR2-spec. engine) is 120 lbs./sq. in. The complete
description of how this is measured fascinated me in reading it: "(With
three Sparking Plugs fitted and compression gauge in fourth cylinder
engine warm, throttle set at tick over, using 20 SAE oil and operating
the starter)"
Anyway, those numbers seemed a bit low for a TR3A, so I looked up the
figures for the "Special Order" engine for TR4 (which, of course, is the
1991 cc. engine). Spec's for that are 145 lbs./sq. in. -- this from the
TR4 factory workshop manual.
> Any opinions on how wide a variance I should see among cylinders before
> I become concerned that there's a problem?
Rule of thumb is around 10% or more, although <5% would be better still.
--Andy
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