Hi Charles,
I once owned a 1977 GMC van with a 350 carbureted engine. I bought it (ab)used and it used 1 quart of oil for 500 miles,
I started using 20W-50 oil as the back plugs would foul with oil in the course of about 5000 miles, and I would have to
pull them and clean them. It also would run rough if it was idled too much and would clear up once out on the highway.
I pulled the valve covers and found oil sitting there. The problem was the oil drain holes in the head were plugged and
the oil was going down the valve stems into the piston chambers. I plunged out the holes with a coat hanger and the
entire problem went away. I then got over 2000 miles to a quart of 10W-30 and the plugs never fouled again.
On this same vehicle I installed a GM professionally rebuilt carburetor and then immediately had to have it
repaired/rebuilt by a local small engine place, who put the proper Power valve spring in.
FWIW.
Kevin

Charles T. Low wrote:
Thanks, Terry,

A marine mechanic to me is a bit like a hairdresser to my wife - we have a
relationship, and I feel loyal. That might interfere with getting my carb
maintained, however, and I'll have to think about how to approach that. I'll
come up with something. Step number one will be to replace my distributor
cap, rotor and leads (they have to be specially ordered - old engine,
1978...) and then reassess.

====

Charles T. Low
www.boatdocking.com

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"Terry Spragg" wrote in message
...

One should expect it to be somewhat better, and in no qualified hands,
ever the worse for care.

My old zenith carb was worn so bad that the throttle shaft rattled on
idle, its' fibre end washers worn way out, delivering varying amounts of
vacuum leak into the intake manifold, which really made life with the old
girl an erratic thing, to say the least, particularly when lower power
settings were needed. As well, a somewhat sticky needle valve must have
been able to stick either open or closed, mysteriously and capreciously.
It's better, now.

Fixing a carburettor is an essential basic automotive and boating skill
which, thanks to induction fuel injection and computerised engine control,
is becoming a skill of the past. If your mech is dubious, you need a real
mech.

A couple of small rubber "O" rings on the ends of the shaft, retained with
a little brass snare wire seems to have steadied the engine up
considerable.

Trry K