First of all, thanks to everyone on the list for help
in diagnosing my gauge troubles. The tach problem was
indeed a bad ground, and the speedo problem was indeed
a binding cable. The tach now works great, and after
re-lubing the speedo cable with dri-slide, it's smooth
as silk. This list is truly wonderful.
Now I have a running problem I need help with, and I
don't really know where to start. First of all, this
problem (or something very similar) was diagnosed by
the list months ago as a potential stuck float, but
the problem vanished before I could figure out whether
it was truly a float problem or not...
Here's what's happening:
When the car is very cold (when it's been sitting for
a day or two in 30-45 degree weather, it runs like
crap when I first fire it up. It's stumbly, down on
power, and rough. It doesn't pull cleanly either
under load or in neutral. It feels like either an
ignition fault or a fuel delivery fault, because you
can tell when driving it that it will "clear" for a
fraction of a second and pull clean, but then
immediately starts stumbling and coughing again.
There is a very occasional and very mild backfire
sometimes. The position of the choke will affect the
idle speed as normal, but has no effect on the running
condition.
The temperature will come up to normal operating range
and the car still runs like hell. Then, after about
20-25 minutes of running, it will clear and run
beautifully. Absolutely perfect.
The stumbling will NOT reappear unless I get stuck in
bumper to bumper traffic and the car has to idle for a
long period of time (say, 5-7 minutes). If it idles
for a long time, the stumble will return, but a minute
or two of open road running will clear it again
relatively easily.
Assuming the car is running well, I can park it and
restart it without any stumbling returning. And even
if it gets cold, but not TOO cold, I can start it and
run it again without much stumbling, if any. Only
when it sits again for a full day or two and gets
really cold again will the whole cycle be reset.
Here's what I know:
The plugs are new and good. They look good, with no
carbon or crap on them. I sorta guessed at the gap,
but I think it's at least darn close to correct, and
besides, the car ran well with this gap before. The
plug wires are new, and the sport coil is pretty new.
I DID screw around with the carbs a little bit
recently, trying to adjust them correctly, and I guess
it's certainly possible I screwed something up, but I
followed the directions pretty closely and everything
seemed to go fairly well. The car ran fine after
that, at least until the weather started getting
really cold.
Oh, and when we get an indian summer day and it's warm
out, the problem still exists but is dramatically less
severe. It clears up much, much more quickly.
Any ideas on what might be happening? If it's a
possible stuck float, I am still a little hazy on how
to determine whether that's the problem.
Disconnecting a hose to the charcoal cannister or
something?
Sorry for a remedial lesson in diagnosing fuel/spark
problems, but any help would be much appreciated.
=====
Paul Misencik
1971 MGB Vintage Race Project
Huntersville, NC USA
www.sopwithracing.com
Learn the truth at www.misleader.org
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