As I have posted previously I just got my car running. Its a 306, mild cam, performer intake and perofrmer 600 carb. I set my timing at aprox 12 deg with the vaccum advance line off and it seems to run pretty good. but when i do put on the vaccum line it starts backfiring out he exhaust. which means its firing when the exhaust is open. so am I a tooth off then? and when the vac adv line is off and i rev above 4000 it backfires once or twice when comming back down.

As for my vacum line I hooked it up to the left port as shown in the diagram that i have for the 1400 series setup. It says to use the port on the left hand side (if looking at the carb from front) if the distributor is vaccum timed (no vaccum at idle).Ihave a stock 83 302 distrubutor. what would this use then? carbvaccumor manifold vaccum (vaccum at idle)???????????????? I can try again tomorrow to double check but i would like some input first!!! I don't know what the original setup is because it was a v6 and I pulled that out about 4 years ago.

 

You want ported vacuum for a vacuum advance. Which means, there will be no vacuum unless the throttle blades are opened a bit. You can easily check this by unplugging the port you want to use. If there's vacuum present, don't use it.