Tyson wrote:
> My SUs are on and the car is running. I have some
> tuning questions. I understand that the carbs are
> the thing to do last, and that valve clearances
> and timing are supposed to be set first.
>
> I set the timing to 12 deg BTDC @ 1500 rpms
> dynamically. I was going by a 73-74 spec. Does
> that sound right? With the idle screws all the
> way out, I can only get it as low as about
> 1100rpms. Also, when I mash the gas, the idle
> speed doesn't always go back. The throttle shafts
> on these carbs have no wiggle.
The clue here seems to be that the carb throttle shafts and butterflys are
sticking. Were these carbs recently overhauled with new shafts and bushings?
They sometimes err on the side of being a little too snug, and need a bit of
a polish on the shafts to get enough freedom to snap back closed with the
return springs. Are the choke fast idle screws fully released, with about
.003"clearance under them?
Are there possibly any other ways air is getting into the intake somehow. A
vacuum line off or chafed, a loose fitting hose?
When I lift the piston pins at idle, the speed drops for a few
> seconds then picks back up.
This would normally be a sign of being too lean, again causing suspicion
that there is another air leak somewhere.
>
> I have listened w/a piece of tubing for whistles
> indicating air leaks, and about the only place I
> can find is at the air cleaners.
>
> What else do I need to do to get the idle low
> enough? BTW, the car dieselled a lot when I shut
> it off. It had been idling a while and the temp
> guage was getting right past the N.
Don't worry about the dieseling. That was caused by being up to the high end
of temperature combined with too fast an idle when the ignition was shut
off. Cure the idle speed and there won't be any more dieseling.
Rich Chrysler
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