Popping sound in exhaust

dart_68 said
Update:

When I pulled and plugged the vCan that solved my popping problem. Motor runs pretty good and I got the idle down to 800 in neutral by turning the idle speed screw. I put a timing light on it and it was at 40* advanced. Wth? I'm wondering how it can idle that low and smooth with 40* initial advance? Is it possible that the dizzy pickup wires are reversed?

FYI, it has a Mopar distributor with HEI.
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I think you need to check if the TDC mark on the balancer is in the right place. You'll need a piston stop ans some patience. There are directions on this site someplace. Or watch this video, although he shows an adjustable pointer which you probably don't have. You need to mark the balancer exactly 1/2 between the two marks: