Now that my gas pedal height is adjusted the way I like it, I'm having
another problem today. If someone can explain this, I'll appreciate it.
I run a Holley Street Avenger carb on an LAT low rise Tiger manifold.
The carb butterflys were not completely closing, unless I tapped the
pedal a bit from idle, and the RPMs were hanging up a bit (not coming
completely down to idle RPM). I figured the carb wasn't centered
properly, or maybe the butterflys were hanging up on a gasket or
whatever. Off came the carb. One of the carb base gaskets did look a bit
suspect so I trimmed it off a bit around the openings. I made sure
everything closed easily with the carb off, which is does. Then I
re-installed the carb, tightened it down, tried it and the butterlys
closed very positively with no hesitation, just from the on board carb
return spring. I started up the Tiger and, with the engine running, the
butterflys do not close completely on their own! Engine off, (nothing
else changed) they close perfectly. I installed a heavier back up return
spring and it pulls the butterflys shut at idle, but I wonder why this
is necessary (I don't mean on the safety issue, but just why they need
an extra spring to close only with the engine on).
I know I should use that extra return spring for safety, but why do
those butterflys want to not close all the way at idle, but only with
the motor on?!!!!
Another related question: The carb has vacuum secondaries. With the carb
off, when I get the primary butterflys open, and then push open the
secondaries manually, when I let the primaries close, that assembly
pulls the secondaries almost closed, but leaves them just slightly open.
Not being able to watch the secondaries in action (I tried riding on top
of the engine with Jane driving so I could look down the carb, but its
too hot and windy to stay on there very long), is this normal secondary
operation? I wonder if the vacuum changes when the engine is on load,
and off load, closes the secondaries completely.
Advice and explanations will be appreciated, as usual.
Steve Sage
1967 MK1A
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