Holley 1920 Stumbles

Send me a PM on the carb -- both it and I are in Seattle, so local pickup would be possible. Check the vacuum advance by removing the vacuum advance hose from the carburetor and applying mouth suction, then capping it off with your tongue. The vacuum should hold til you remove your tongue from the end of the hose. If not, and the hose itself is good, then new vacuum advance (or new distributor -- got one of those, too -- and HEI upgrade ). If you do this test while pointing a timing light at the timing mark, you should be able to watch the vacuum advance work. If it doesn't, fix that. And what have you got base timing set to?