I may have done some serious damage - or maybe I'm luckier than I think.
The initial problem...1973 MGB with HIF-4 carbs would not start and was
trickling fuel out the vent line.
Upon disassembly of the front carb - I found the float was gasoline solid.
Lacking a spare float and trying to get ready for a club outing, I drilled
two small holes in the float to drain it. I then applied a bead of permatex
which was SUPPOSED to be fuel-proof. It worked for about 45 minutes, but
fortunately I came to rest in a friend's driveway.
I pulled the fuel line from the front carb and connected it directly to the
rear, figuring that for the 2 miles of back roads, I could use the choke and
the rear carb to keep it running.
The first several tenths of a mile was fine, as the front carb was full of
fuel. Once it ran out though - I had some nice backfiring due to the lean
mixture. I nursed it home and pulled the carbs and ordered new floats.
Upon reassembly - it ran OK, but not as smoothly as before. I drove to work
and back, and was convinced that the mixture was off a bit. Looking at the
jets - the rear one was much higher than the front one. This puzzled me as
I didn't change the jet settings when I replaced the floats, and both were
very close before.
I pulled the piston and cover off each - and notice that the needle on the
front carb has some carbon on it - probably from the backfiring.
The present symptom is a 500 rpm swing in rpm, no matter where the throttle
is set, and more noticeable when it warms up. If I hold the pedal for 1500
rpm - it will drop to 1000 rpm for a second or two, then climb back up to
1500 for a few seconds, then fall back down to 1000 again. If I set the
idle at 1000 rpm - it drops to 500 and stalls out.
Naturally - this happened last night - the night before our club meeting -
so I'll "drive 'murican" again. :(
Any guesses as to what happened? I'm sure hoping I didn't burn anything.
Thanks,
Rich Mason
'73 MGB
Madison, AL
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e-mail--> rmason@ro.com
MG Page-> http://ro.com/~rmason/mgpage.htm
NABMS --> http://www.geocities.com/MotorCity/Garage/5207/
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