Listers:
Yesterday I noted that my front Zenith-Stromberg carb was running very rich
(making plugs 1-3 get very sooty and misfire) even after balancing the carbs.
I asked some advice about using the special tool to lean out the mixture.
I had already ordered the mixture adjusting tool from TRF but it hasn't yet
arrived.
I called TRF this evening to check on the delivery of the adjusting tool.
It is on backorder. However, Dave from TRF was kind enough to spend some time
with me on the phone discussing the problem. He suggested that it made
little sense that the front carb would all of a sudden begin to run rich
unless
it was malfunctioning, and that leaning out the mixture was probably an
attempt to compensate for a different problem. He suggested checking some
other
things before adjusting the mixture:
1. Check the fuel pressure with a gauge to make sure that it was low
enough (1.5-2 psi, if I remember right). If too high, it can make the front
carb
run rich compared to the rear. Pump overpressure can occur if valves in the
fuel pump stick or wear out.
2. Take the float chamber off the carburetor and see if a float is
cracked and full of fuel. If so, extra fuel can enter the combustion chamber.
3. With the float chamber removed, remove the metering needle assembly
and look for dirt. If the metering needle gets stuck, it can let extra fuel
into the combustion chamber.
I'm not sure if I got the details right, but it makes sense to me that a
mixture adjustment shouldn't get way off for no reason on only 1 carburetor.
Does this make sense to you?
Thanks.
Michael
'76 Tahiti blue
CF 57044U
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