total advance ?

louie said

on my rebuilt stock 340 with electronic ign, timed it to tdc ,mechanical 29 degrees without vaccum. total advance with vaccum hooked up 48 degrees does this sound right.this thing runs great but i thought it should be around 34 degrees total? there is no knock or pings and i shouldnt complain just was wondering what u all had total advance.

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As moper stated the vacuum advance only operates at light throttle cruising. When connected to the timed port on the carb it does not operate at idle either.

The total everyone talks about is initial plus the timing in the distributor. Your distributor has 29 degrees in it (0 initial according to your post). If you bring the initial timing to 5-7 degrees before TDC you will have your 34-36 total.

The vacuum advance will have somewhere around 17 degrees in can. The sum of the total and vacuum is 53 but that much will seldom be added in. When cruising at light throttle the max vacuum advance will be added but the rpm's will most likely be lower than the max mechanical.