As a friend of mine says, one test is worth a thousand theories. Hook up a
timing light and watch what the timing does when the idle is rough. If it
puts on a light show, you've got distributor problems. If not, you need to
look elsewhere.
Next place to look would be carb synchronization. The rubber hose trick is
good enough, just use a chunk of hose to listen to the hiss at each carb
intake. If they all sound the same, the carbs are synchronized.
Adrian's suggestion of a vacuum leak is good, too.
When you've exhausted all other possibilities, I'd start being suspicious of
that "warmed over" cam. It's not unheard-of for aftermarket parts to be
defective, and one lobe slightly out of place (or a bent camshaft) can
certainly affect idle quality. Get a dial indicator and a degree wheel,
check that all the valves open and close when they should.
Although the Crane will compensate to a large extent for slop in the shaft,
it can't do anything for wear/damage to the centrifugal advance mechanism.
-- Randall
** triumphs@autox.team.net **
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