Help with Backfire

RustyRatRod said

Think about your intake valve hangin open theory. If it is poppin, that's the cylinder firing. If the intake valve is hangin open, it would not fire, because there would be no compression. Something is causing the exhaust valve to stay closed, IMO. The cylinder still fires, but the exhaust is forced back up through the intake.

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If it gets any fresh charge in, it can still fire back up into the intake. It does not need compression to fire.... like fuel out of the exhaust firing off and ignition timing being wildly off and back-firing up the carb while the intake is still trying closing.

But it seems like the OP found it...on the exhaust side so someone gets a prize! That is good.