Working on a 140 with Holley 2bbl carb.it has the usual flat spot, hesitation issues, but the big problem is the idle. You can adjust it to stay running and it idles too fast. Try to lower it and it goes too low and stalls.

Innards of this engine are unknown, but, has a hot cam. These are the things I've checked:
Compression
Float level
Vacuum leaks
Has correct distributor, initial timing 18 degrees
Vacuum advance hooked up and working

Is this idle issue another inherent problem or is there something I'm missing. By the way, when I got the car from the previous owner, the vacuum advance was disconnected.
Thanks for your kind attention.

Frankford, De., eight miles north of Ocean City, Md.
1966 Corsa convt.

Low runner velocity and cool runners cause fuel to drop out, causing lean idle mixture I'd suggest bumping the timing up a couple of degrees. It's a common problem with center 2&4 bulb conversions. Adding intake runner heat is another cure.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
65 Canadian Monza 4dr 110/PG 40k
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

Wagon master. Won't be near car again until Tuesday. I'll try to collect that info.

Frankford, De., eight miles north of Ocean City, Md.
1966 Corsa convt.

Where is the vacuum advance connected? Needs to be connected to a ported source, on the carburetor as opposed to connected directly to the manifold. If it’s connected directly to the manifold, you’ll have too much advance and won’t be able to get the mixture and idle speed screws properly adjusted.

Chuck vonHofen
Brentwood, California

66 Corsa Turbo Convertible
64 Spyder Coupe
Too many boats
Amazingly Patient Wife

Advance to Venturi vacuum.

Frankford, De., eight miles north of Ocean City, Md.
1966 Corsa convt.

Which Holley are you using? There are a number of different vacuum port arrangements, some with full manifold vacuum and some with timed vacuum based on throttle position. Just to clarify, with the engine running at idle, you should have no vacuum signal to the vacuum advance. You should be able to disconnect the vacuum line and see no movement of the arm and no change in spark timing. You should only see movement of the arm as you start to increase the throttle setting.

Chuck vonHofen
Brentwood, California

66 Corsa Turbo Convertible
64 Spyder Coupe
Too many boats
Amazingly Patient Wife