Howdy all,
I noticed a strange problem with my MGB. It had a little
stumble at low rpms under load until it fully warmed up. No matter
where I put the choke, it still acted up. Oddly enough, it just
started this week. I thought I might have some carbon build-up, so
I wound the car through the gears to no avail.
To make things even weirder, I had a funny little problem where
my idle speed while on choke would be about 1000 rpm. Once the car
was warm and the choke was out, it jumped to 1500. The engine
wasn't racing, just idling high. I checked multiple times to be
sure that my choke linkages were in the right places and my mixture
was set right, but I found no mistakes.
Then today I decided to turn the timing back a touch to drop the
idle. I did, and the car was a turd. I felt that I'd be better off
with a high idle and power than otherwise. I loosened the bolt on
the dizzy with the car running and started advancing the timing. I
turned the dizzy past my original point, and was astounded to hear
my idle drop!
I clamped the bolt down and drove the car - it ran better than
before, but not much. The most noticeable effect was a slight
backfire when downshifting - of course, this could be due to small
exhaust leaks. So, I'm wondering, is there a point in the timing
where the idle will be at it's highest, and after that point the
idle will drop, regardless of whether advancing or retarding the
timing? On the same thread, can retarding the timing too much cause
the starter to lug when trying to start a car when it's warm?
FWIW, I just went out and tested the car while it was cold. The
car idled at about 1200 on choke, 900 rpm without. I guess that's
pretty close to factory specs; if I remember right the manual says
something like 1200 choke/1000 w/o. The car also warmed up much
faster than normal too - keep in mind that it's 40 deg. F right now,
so morning temps aren't going to be much colder.
The important thing is that my timing changes appear to have
fixed any ailments I might have had. Can increasing the timing
enable a car to burn _more_ fuel, or does it just enable the engine
to burn it _more effectively_? I'd like to know why this stuff
happened. What do you folks think?
Michael S. Lishego
http://www.geocities.com/MotorCity/Speedway/3706/
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