Details: 1950 3100, 216 engine, running a Carter YF carb, aside from the Carter carb, all else is stock.
I recently starting chasing down what seems to be a fairly quick onset of a backfire.
I noticed it at first on deceleration. I tracked that down to being a little too rich on the carb and leaky exhaust manifold donut gasket.
In the process, replaced worn points, reset timing, points gap, cleaned and regapped all plugs, readjusted the carb and it seemed to go away.
I have it running smooth as can be, until the engine gets really fully warmed up and the backfiring seems to return.
It's consistently not backfiring when it's first started and just getting warmed up. Runs fine for five minutes or so with choke wide open, then starts popping under a little load at maybe 2500 RPM (guessing, didn't check it yet).
I realize diagnosing such in post can be difficult, but I've read (and learned) much from the experts here so I'm hoping someone can help get me focused on the next steps more quickly.
Thanks in advance.
