Does your carb have a poppet valve in the throttle plate? If so,
check to see that the poppet isn't sticking or fluttering open. Take
a hose and stick one end in the throuat and the other on your ear. If
the poppet is fluttering, you will hear a pulsating sound.
If the poppett is fluttering or sticking open, you will not be able
to control the idle speed and it will be too high. I had this problem
with my TR8 (twin z-s) and it took quite a while to figure this out.
The poppet valves are not covered in the Haynes manual. I have no idea
what goes wrong with these things, whether the spring weakens with
time and heat or what, but they are put together with solder and
you can unsolder then to replace the spring or, as I did, merely
crank down on it a bit to provide more force.
The poppet valves are there to prevent backfiring on decelleration,
by the way.
Wayne Simpson
1980 TR8
|