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red82gt · 02-04-2002, 05:19 PM

Vacuum is better for a street car, when cruising at part throttle the timing doesn't advance so you'll get better fuel economy and at part throttle acceleration the curve will advance faster from the change in vacuum, whereas a mechanical advance is controlled by the engine rpm.

For a drag car that doesn't need fuel economy, driveability or part throttle response and spends most of it's time at full advance (3000+ RPM) then mechanical is the way to go.

If you do go with vacuum advance, find someone who knows how to re-curve distributors, it's becoming a lost art but it makes a big difference.

BTW I'm only 24 and since the mustang mags don't talk much about carb tuning (except for some full blown race motors) I've learned a lot from HOT ROD and from other books about tuning carbs.

02-04-2002, 05:19 PM	#3
red82gt Sober voice of Reason Join Date: Nov 1998 Location: Kelowna, B.C., Canada Posts: 1,514	Vacuum is better for a street car, when cruising at part throttle the timing doesn't advance so you'll get better fuel economy and at part throttle acceleration the curve will advance faster from the change in vacuum, whereas a mechanical advance is controlled by the engine rpm. For a drag car that doesn't need fuel economy, driveability or part throttle response and spends most of it's time at full advance (3000+ RPM) then mechanical is the way to go. If you do go with vacuum advance, find someone who knows how to re-curve distributors, it's becoming a lost art but it makes a big difference. BTW I'm only 24 and since the mustang mags don't talk much about carb tuning (except for some full blown race motors) I've learned a lot from HOT ROD and from other books about tuning carbs. __________________ 393W: AFR 205's, hydraulic roller, TKO600.