I've been having really strange idling issues with the new carbed, mechanical 350.

For instance, ever since my alternator went to **** last week, and I near drained the battery getting it home, it actively refuses to idle above 500 until it's REALLY warmed up. (i try to idle at 1k)

Also, in general, it seems to love to try and die if I'm not super careful with the idle. Like, when coming to a stop or turning with the wheel cranked far to either side (even when really slow). I'm constantly having to keep it in first as long as possible when coming to a stop or slowing to turn to keep the rpms from dropping so low.

I did notice when I first started toying with where to plug my vacuum advance, that when using full manifold vacuum, that the car relies on that vacuum to idle nicely. So, when the rpms drop, the vacuum drops, so the advance drops, so the rpms drop, so the vacuum drops, so the advance drops, so the.... etc, etc, etc. It struggles to break that loop on its own if ever the rpms drop below standard idle.

Thoughts?

 

Why are you trying to idle at 500 RPM? A stock 305 will idle comfortably at 600, but that's mostly the tiny cam.
Manifold vacuum is great with modest cams.

 

Sorry, mine is a 355 with this cam... http://www.compcams.com/Company/CC/c...?csid=216&sb=0

 

Vac advance is not required to get it to idle, but is required to get fuel economy.

Forget it for now - lock it off, and work on the idle issue. Sounds like maybe not enough idle mix or mix incorrectly set. First of all, get the mechanical timing ballparked - about 33-36 degrees btdc at about 3000 rpm. This should reduce back to 10-20 degrees at idle, around 800 ish rpm.

Then look for vac leaks, and get the idle mix right. Should be able to coax a steady idle from it. Then tune timing/fuel/vac advance from there.

Also, that cam is pretty large, with a huge overlap, looks to be over 80 degrees, with a late intake close. Its never gonna be real happy at low rpm. But I suppose that's why you got it.