Thanks all for the ideas. Turns out the exhaust manifold was cracked. I
replaced it and now can't make it backfire. It still runs rich. I don't have
an exhaust gas analyzer so I look at the spark plugs and they are black and
sooty.
The main metering needle, when screwed counter clock wise to the end of the
threads seems to produce no viable smoke on throttle blip, but after drive
the plugs are black. This motor now has no air pump, a hollow "cat." The
manifold to air pump is corked. The vacuum tubes all seal and none are
plugged The vapor canister system looks OK, no hose cracks or leaks and the
charcoal is dry , clean, and odorless .The carb has the proper 44A needle
which seems unscared. The carb diaphragm is new. The oil is topped off. The
piston rises smoothly and drops with a clink. The automatic choke seems to
work smoothly when I open it up, but doesn't raise the idle speed when I
start it up.
BTW, I do have a Bently manual, Haines, Chilton and a collection of Twist
articles. However, I am limited in training, experience and equipment. All of
what I could easily test, I have.
. BTW again, the distributor is a stock one but with an Aliison transplant
with a disk with 4 windows revolving between two eyes. Very flimsy deal that
needed a larger washer under screw to breaker plate. Mechanical advance is
clean and oiled. Vac retard does move breaker plate. The gas cap seals. The
oil filler cap seals. The rocker cover seals and the valves are adjusted.
I have fiddled with the deceleration valve and the idle speed mixture valve,
but since I can't get the main needle adjusted, I gave up on those too.
I'm sure I've not told the whole story but it's what I can remember now.
Please throw some ideas my way again.
The car seems to run OK when warm. Ignition set at 10 before at low idle.
Will sometimes buck or lurch very slightly at speed and cruise.
I have not done a compression test. It will idle smoothly at 700 rpm and will
get up to 80 mph without a strong back wind. Sometimes I see a little blue
smoke on warm up, not much, and not always.
Thanks
Marc Derenzy
79 Midget
74 MGB
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