Distributor is not bad. Electronic distributors can have so much wear that the rotor cuts into the pole-piece,as long as the pick-up is still generating it's tiny signal, the engine will keep right on running.
Now;
the spark from the coil has to jump from the rotor-tip, to the cap-tower as it is whizzing by. If the rotor is not in the right position, the spark can "choose" the path of least resistance, which could be an adjacent tower. If it's the previous tower which is at the end of it's Power stroke, AND
If you are running log-manifolds,
but there is still unburned fuel in the gases when the exhaust pops open, AND the coil pops it off, Badaboom, you get a pop in the exhaust simultaneous with a power loss.
Another thing that can cause popping in a log manifold, unrelated to the rotor, is this. If the ignition timing is late; it is possible for Not all the air-fuel charge to finish burning in the cylinder, and so, it finishes burning in the log. That's fine. But if for whatever reason, the air fuel charge in an adjacent cylinder does not all get burned and enters the log, uncombusted, it can explode there, and there is your pop.
with headers;
the same pop can happen if the head flange is leaking, and the header sucks in fresh air. But in this case, there is no power loss; just the bothersome racket..
Ok now let's say you give it plenty of Idle Advance, say 12*. To the engine, this is still terribly retarded, it may be wanting say 25 or 30.
So now, you put it in gear, and gently drive away. Say by 1500rpm, the V-can is still not on line, but the mechanical has climbed to 18*, but the engine is wanting over 40*. so it's still terribly retarded. Say you get to 2500, and the Vcan has brought in 12*, and the mechanical is up to 12, and you started with 12, so now you're up to 36, but the engine, to complete the burn in it's cylinders, wants 55*; so it's still terribly retarded! So this whole time, the Power stroke has been delivering still-burning exhaust into the Logs/headers, and maybe the popping has been going on the whole time. Now, just step on it a lil harder, and the timing requirement drops to 36, which is what it's getting, and so the popping ceases.
Ok great so you step on it a lil harder and the Vcan drops out, leaving you with 24, but the engine wants at least 30*, so it's stinking retarded again!
Now, what if your intake is sucking air from some place other than the airhorn?, and some cylinders go too lean to catch fire on time, or don't catch fire at all. Now you got a slug of fuel charge entering the exhaust, and if/when it catches fire, badaboom, there's another pop.
