Hello all. I would welcome some advice on one of the carbs on my TR3, #15005.
Itâ??s primarily the rear one that is giving me trouble.
The car has been running too rich for a long while and I decided to sort it out
on the weekend. I took the air filters off. The first thing of interest was a
difference in the behaviour of the two pistons. Both carbs have damper oil in
them. The piston of the front carb was pretty hard to push up - I pushed a good
way, and when I let go it fell quickly down to the bottom with a satisfying
metallic thud. The rear piston didnâ??t offer the same resistance to being
manually displaced upward. It was easier to push up, and when I let go of it,
it fell more slowly down and not with a metal to metal click - more a soft
noise. However, when I removed the damper, it fell quickly and with the same
â??clackâ?? as the forward carb. So itâ??s centering properly I think. I
removed the chamber, spring and piston and cleaned them carefully, and put them
back in, but still exactly the same behaviour. Both carbs have the same damper
oil. So that is one thing that puzzles me.
The front carb is running a bit rich - it shows yellow on the Gunson colortune,
but the plugs are ok and the rpm does not increase to speak of when I lift the
piston a little.
The rear carb, judged by the thick, black layer of soot on the plugs, is a lot
worse. When I lift the piston the revs increase noticeably and stay there. The
trouble is, that even with the mixture adjusting nut screwed totally upwards
itâ??s still far too rich. The car may be sucking a bit of air along the
throttle shaft, but this should if anything lean out the mix.
There is one more thing that might be important, but I havenâ??t researched it
up yet. Just under each carb there is some kind of metal contact with the
exhaust manifold, a kind of metal buttress or similar. It was hard to get a
good look at it today. Well this is wet on the rear one and dry on the front
one. I canâ??t say more just yet until I get a better look at this area. There
is some smoke wifting up from that area after the metal heats up, but it
doesnâ??t smell like burning fuel or oil.
The car runs very well and I think that the rest of the motor is more or less
properly adjusted. Valves are good, breaker gap is correct, plugs are new and
gap correct. Timing is ok. Coil I have not checked, but the car runs and idles
fine.
So there it is. One problem - mixture too rich even with nut screwed up to the
max. One maybe problem - piston of same (rear) carb falls slowly.
Very grateful for any suggestions,
Dave
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