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Just added a Summit electronic distributor, SUM-850306. I set it w/o vacuum advance to 16 degrees. I noticed the engine had to fight the preignition when starting, so I changed that to 12 degrees. Cars seems to run fine, steady idle and takes the gas fine. Vacuum however is only 14.
Then I added the vacuum advance, taken from the port vacuum on the Holley 600. Idle unchanged (of course, it's ported vacuum), but when accelerating it pings and explodes in the exhaust, clearly too much advance.

It would be tempting to leave out vacuum advance, but I think it affects mileage. Mileage is not something I can ignore, this is to be my daily driver and gas costs $10/gallon over here.

Any suggestions:
1. Leave out vacuum advance?
2. Fix so that vacuum advance is limited?
3. Go to full vacuum advance instead of ported, which would of course lower total advance at WOT

I can go trial and error, but any advice my save me some time.

According to the instructions from Summit, the springs they use for standard (silver/brown, must be similar to gray/brown) have the follwing advance (crankshaft degrees):
RPM 1000_1500_2000_2500_3000
Adv ___0____5___15___24___24 (factory set limit)
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