backfire throught the exhaust

[MedPhys]

I'm not very knowledgeable about ignition timing.  If I had a backfire through the carb and the motor wouldn't start I would think that the distributor might be in 180 degrees out.  What if I get a backfire through the exhaust (very loud, I think a woman nearly peed herself based on the scream she made), but the engine will eventually start?  Which way would I need to rotate the distributor, or what could cause this?

[firefighter3931]

I'm not very knowledgeable about ignition timing.  If I had a backfire through the carb and the motor wouldn't start I would think that the distributor might be in 180 degrees out.  What if I get a backfire through the exhaust (very loud, I think a woman nearly peed herself based on the scream she made), but the engine will eventually start?  Which way would I need to rotate the distributor, or what could cause this?

A backfire through the exhaust is caused by the ignition firing while the exhaust valve is open. It could be ignition related (timing) or the valve may be sticking open.



Ron