[JimNolan]

Guys,
Will someone that knows answer a question for me. Does the vacuum advance adjustment screw limit the amount of advance at high vacuum or does it just limit the rate the advance comes in at.
I've not had trouble with my car pinging but I did have the engine surging at @ 35mph. I turned the screw out a couple turns and that took care of it. I assumed I had limited the amount of advance by increasing spring pressure inside the cannister. Jim

 

[captionwell]

I have a lot of personal experience with these, no pro, but I hope I can help. The vacuum advance changes the rate it comes in at, not the total, that is controlled by your centrifugal and initial alone. Turning in (CW) decreases the tension and allows the vac to come in to play early, turning out (CCW) increases the tension and allows the vac to come in late.
Perfect way to set it is to back out about 6 turns and then cruise up a hill, about 35 mph, light on the throttle and turn in one until it pings, surges and/or hesitates, then back off two turns. You will know it is dialed in when it 'floats' around 60-65 mph and has a smooth acceleration to cruise feel.
If your car is pinging then back off the total timing until the ping goes away at full throttle acceleration (should be about 34-36 for most ford engines) and then adjust the vacuum advance as written above. Heavy cars like earlier advance rates btw, lighter springs for the centrifugal are a great idea. Good luck!!!

 

[PaleRider]

Guys,
Will someone that knows answer a question for me. Does the vacuum advance adjustment screw limit the amount of advance at high vacuum or does it just limit the rate the advance comes in at.
I've not had trouble with my car pinging but I did have the engine surging at @ 35mph. I turned the screw out a couple turns and that took care of it. I assumed I had limited the amount of advance by increasing spring pressure inside the cannister. Jim

Depends on the can; while Moroso lets you adjust the amount of advance Cranes cans let you adjust the rate, amount by a "cam". Accel gives you both rate & amount, not shure of Mr.Gasket, I prefer the Crane-kit w. springs.


Moroso 72315 - Moroso Adjustable Vacuum Advance Kits - Overview - SummitRacing.com


Crane Cams 99600-1 - Crane Vacuum Advance Kits - Overview - SummitRacing.com


ACCEL 31035 - ACCEL HEI Adjustable Vacuum Advance Canisters - Overview - SummitRacing.com