FINALLY - Vacuum Advance Dilemma Solved

[Gaz64]

Originally Posted by DAVID GAGNARD

An easy way to tune a holley weather it is vac sec or double pumper is:
get the engine fully warmed up and put a vacum gauge on it and begin turing your idle mixture screws in or out and watch the vacum gauge, your looking of for the highest reading possible, do one screw at a time, when you get the highest reading, move to the next one, you'll have to re-adjust your idle speed and you'll have to go around the carb 2 or 3 times to get it to the highest point, then take it out on the road for a test run.........this is also assuming your timing is correctly set from the get go.......
Not sure if you can add vacum advance to a mechanical distributor using an MSD distibutor, you could call the MSD tech line and ask.....

David

And then with the engine off, wind all the screws in until seated counting the turns as you go.
Back them all out to an average of all the screws and tweak each one for highest vacuum at idle, making a mental note of where all the screws are relative to seated position.

Originally Posted by brandx

Timing and carb tuning go hand in hand. Just wondering how many of you use a air fuel meters to tune your engines. After reading the very well written article on vac advance It seems as though the cruise timing is about the same as my mech. The difference seems to be in the idle. Here in utah I have to pass an emissions test. If my idle timing is beyond about 8 degrees it wont pass.

I have two Wideband O2 data loggers that I use on my cars.