The engine started right up after just a few cranks but wouldn't idle at all. I had to crank the idle stop screw to raise the rpms up to about 1200 or else it would stall. I unplugged the vacuum advance and checked the timing. The balancer is only marked up to 12 deg before TDC but the timing light showed much higher than that, I'm guessing 20. So I backed the timing down to 12 and adjusted the idle mixture. The engine ran best with both screws out a total of 2 1/2 turns and I was able to lower the idle down to 900, but the idle was still very rough.
I hooked up a vacuum gauge under the carb and discovered the engine was only pulling 6 inches at idle. Very poor. That explains why it won't idle smoothly. I'm not sure what to do at this point. I'm pretty sure there's a vacuum leak somewhere. Hopefully it's under the carb and not the intake manifold. And I'm still not confident the carb is performing correctly. With the low vacuum I'm not getting enough airflow for the carb to meter the fuel properly.
UPDATE:
I decided to checked the intake manifold bolts and boy was I surprised. They weren't loose exactly but they weren't torqued any measurable amount. So I torqued them down in stages to 20 ft/lbs. With my fingers crossed I started her up. The idle did seem a little better but I still only measured 6" of vacuum. I was more than a little disappointed since I thought I had fixed the leak. Now I'm pretty certain the manifold must have been leaking before I tightened the bolts, and I'm guessing it must still be leaking. I've ordered new intake gaskets so stay tuned.
