Vacuum/ in gear idle issue.

GDL said

Ok, so the 340 is giving me fits. Timing is about 13 degrees initial and full 36 with the vac canister hooked up. However I think the carb has a vac leak since I was hearing a high pitched whistle (thermoquad) which just developed. So my question is if there isn't a vac leak and would an adjustable canister help for vac advance since the distributor is the original 318 2 bbl distributor?

And my issue is it's seemingly hard to start (buying a new starter) and idle is at 850 rpms but in gear it's dropping about 400 rpms... Ideas?

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What sort of ignition are you running?
It would work out to your benefit to find out what it wants to start better (more fuel/less fuel) then you have a direction.

I'm kind of wondering if maybe you have a low powered spark and some miss tuning.
The mini starter would help a little if this is what it is because they take less amps to turn the engine over and this may leave more power for the coil.

The whistle may very well be a vac leak, or an internal gasket leak.
Can you use a small hose and narrow it down by using it as a sort of stethescope for the source of the sound?