Foreign I'm sure. I have a GM factory also with same result. J78 pole piece is what I know as pick up coil. The odds of 3 different pick up coils being bad is astronomical. But possible. I can't see how valves could have anything do with it, or the carb unless the ports blocked... But I get a full 15in of vacuum from manifold vac. And the advance can is full advance at 15in. Iv been hunting an ignition rabbit but I think in the wrong places. Possibly the balancer spun?!?!?! But there's a key for the balancer shouldn't that keep it from spinning? Obviously its gear drivin timing between cam and crank, couldn't see it running as well as it is being a tooth off at timing gears or at dist. Its set at 10* btdc as all my 250s were. I may be in the dark as to what exactly plays into over all timing. Not talking about "over all timing" per say but what mechanical parts can be faulty to thro it off.
