Holley Avenger spark advance port sends dizzy off by about 100 degrees advance

crazypete · 10-21-2002, 10:05 AM

I'm doing a carb conversion on a 91 and she idles like a charm. I set base timing at 10 btdc with the vacuum advance disconnected on the distributor. She's idling at roughly 1100 rpms. No problems. Now I pull the plug off the vacuum advance port on the carb (with surprisingly no change in the motor idle speed) and plug in the distributor vacuum hose (an 85 mustang distributor with the steel gear) and I see the timing marks shoot so far advanced that they end up UNDERNEATH the engine somewhere (I had the light on it the whole time). I hear bang bang pop bang as the car now happily detonates away. My manifold vacuum is about 15 @ 1100 rpms ...20 @ 2000 rpms (isnt it supposed to go down?). What am I doing wrong? The car even revs without vacuum advance with no detonation...even if I GUN it. Is mechanical advance good enough?

10-21-2002, 10:05 AM	#1
crazypete Registered Member Join Date: Sep 2002 Location: Boston Posts: 592	Holley Avenger spark advance port sends dizzy off by about 100 degrees advance I'm doing a carb conversion on a 91 and she idles like a charm. I set base timing at 10 btdc with the vacuum advance disconnected on the distributor. She's idling at roughly 1100 rpms. No problems. Now I pull the plug off the vacuum advance port on the carb (with surprisingly no change in the motor idle speed) and plug in the distributor vacuum hose (an 85 mustang distributor with the steel gear) and I see the timing marks shoot so far advanced that they end up UNDERNEATH the engine somewhere (I had the light on it the whole time). I hear bang bang pop bang as the car now happily detonates away. My manifold vacuum is about 15 @ 1100 rpms ...20 @ 2000 rpms (isnt it supposed to go down?). What am I doing wrong? The car even revs without vacuum advance with no detonation...even if I GUN it. Is mechanical advance good enough?