Forget about balancing the carbs and any other adjustments.
First thing it to deal with the center carb.
No clunk = jet not centered. If bad, this can hold the piston
above its rest, and mess everything up.
So first, center all the jets again, just to be sure.
Adjust the mixtures full lean, i.e. jets at the very top of their
travel. Lift each piston and let it fall. Any that do not drop
with perfect ease and smoothness have to be changed.
Do the whole jet centering thing from the book over again
until the piston falls smoothly and clunks. If you are finished
adjusting and no clunk, start again.
If you can’t fix it to clunk, try removing the needle entirely and
dropping the piston. If still no clunk, your dashpot damper is
interfering either through bend rod or other – alternatively, the
bearing mechanism for the piston has some interference from
corrosion or damage. Get that fixed.
Once you get full rich clunks everywhere, rebalance the
carbs. I find visually works super. Just watch the fast idle
screws very carefully to detect when they just begin to budge
and insure that happens at the EXACT same time. If this
procedure does not result in evenly balanced carbs using
the Unisyn or other tests, then you have other problems.
Verify nut tightness, vacuum hose tightness and integrity,
and gasket integrity downstream of the carb. Any of those
could be letting more air in beyond the carb’s control.
If all that is perfect, your butterflies may not be installed
To fix the butterflies you have to remove the carb
and loosen the two screws holding them in, just a little till they
can move around in their shaft. Close the carb and make the
butterflies move until they completely close up the throat. At best,
little or no water will pass through when you hold them closed
and put water in the throat. Then reassemble and balance
using whatever method you wish.
While you are in there check the shaft for clearance – there
should be seals in there that eliminate any bleeding of air in.
If there is any slop, get them reworked by Joe Curto or another
experienced person. Or try doing it yourself.
Make sure the Choke linkage is not applying any force to the
jets or the fast idle screws. In fact, you can just unscrew the fast
idle screws way out of the way until the basic carbs are well
Then you have to get the idle down to about 500 RPM before
you adjust the mixture. Maybe 800 will work, but you should be
able to eventually get a nice smooth idle at 500 after doing some
preliminary adjustment. Then do the book procedure. You
have to observe the RPM very closely to detect the rise nd fall
that the book prescribes. You can go back in the archives and find
a lot of tips from many people about alternative ways to adjust.
But you will never get anywhere trying to work around some
problem, and adjusting from there. Everything has to be perfect
(including points, plugs, timing, valve settings, etc.) But the
payoff is you’ll never have to fool with them again. BTW, after
they are perfect, never adjust them again – the problem is
elsewhere unless you see fuel pouring out.
Jerry Mouton “Laissez les bons temps rouler!”