You write:
> I recently checked compression on a '74 Spitfire that I have begun rebuilding
>.
> Although it looks fairly goog, I'm not sure what a "healthy" 1500cc Spitfire
> engine should have.
> My results were: #1 130
> #2 128
> #3 130
> #4 125
These numbers sound in the right ballpark to me. One of the most
important measures in a compression check is that the compression is
even. In other words, the highest and lowest compression figures should
be close to each other. (5% tolerance is excellent, 10% is generally
acceptable, and 20% indicates it's time to fix it! By the way, all
"zeroes" doesn't count... :-)
Your figures are all within 5%, indicating a healthy engine from my
point of view. As to the actual magnitude of the figures, numbers around
130 psi are typical for Triumph engines.
> Also, I did a tune up on the engine and set the timing to the 2 degrees
> ATDC that my Haynes manual (and the decal under the hood... err, I mean
> bonnet) and the engine doesn't run as well at an idle. The timing was
> previously more like 8 degrees BTDC. Is my timing info wrong?
You may have already done this, but the timing specifications are for a
specific RPM. It is best to rely on an external meter (not the tach) for
idle speed. If the timing has been set at the wrong RPM, it won't run
well. I don't happen to have Spit 1500 timing specs handy, though.
--ken
Kenneth B. Streeter | EMAIL: streeter@sanders.com
Lockheed Sanders, PTP2-A001 | WWW: http://rassp.sanders.com/streeter/
65 River Road | Voice: (603) 885-9604
Hudson, NH 03051 | Fax: (603) 885-0631
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