Holley 1920 carb issues!

Big issue that can cause all kinds of problems is fuel pressure from the mechanical pump. I worked with carb rebuilder that specs max 3 lbs pressure. I checked mine and it hit 7-9 lbs. Put holley regulator on it set at 3 lbs and all the problems went away and it starts first key turn everytime. The mechanical pumps will drive you crazy if you don't control them. I know this because I had my carb rebuilt also and got tired of the constant problems. If you want to seriously fix the problem, just get a fuel pressure gauge from local parts store and see for yourself.