This weekend I took my '74 MGB on an extended tour (see Hocking Hills
post) and the car ran fan with no real problems except overheating
somewhat and stalling while idling. I've never been able to set the
timing according to spec because for the car to run the timing mark on
the pulley has always been nowhere near the timing marks on the timing
chain cover. I always just assumed the timing mark on the pulley was
off, maybe I had the wrong year pulley -- it's a '69 engine in a '74 B,
maybe parts were combined was my theory. Anyway, last night I got to
thinking that maybe the high running temperature was due to
over-advanced timing. The car also seemed to be either pinging or
having rattling valves during a very narrow band dependant on throttle
position (when the throttle was opened just a little, open it a lot
and it was fine.)
I finally decided to see how far off the timing mark was by pulling
the #1 plug and finding TDC. Guess what, the timing mark was right on.
This means I've been running probably 35-40 deg. BTDC (can't really
tell because it's so far off the scale.) Spec says it should be 10
deg. static timing or 14-20 deg. (depending on which book I look at) dynamic
timing. Well, I tried it at 10, 14, and 20 deg. BTDC and while it
does idle somewhat better, under load it bucks and sputters and
backfires (gee maybe it wasn't the Weber that was my problem.) I
haven't reset it back to where it runs well yet, I wanted to get some
opinions on why it would require so much advance to run well. The car
currently has HIF4 SU's, with all of the pollution control stuff of.
BTW, the centrifugal advance does work.
Any thoughts?
Thanks,
Bob
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