Backfire

[river_side]

I am getting an occasional backfire on the driver's side mostly during acceleration only. I am very certain that the timing is correct. The backfire affects significantly the performance. Is there any other cause except valve adjustment? The backfire is not consistent, but often. The backfire occurs through the carburetor. I had previously adjusted the passenger's side, but not the driver's side. If one side is adjusted is it always a good idea to adjust the other as well? Best to adjust warm while running, back out until slight rattle then tighten 1/2 turn? Thanks!

[bbodie52]

Possibly an ignition crossfire to another spark plug? Check the distributor cap (inside) for signs of a carbon track that might cause a spark voltage to periodically jump and fire the wrong spark plug at the wrong time. (Never seen this, but maybe????)

Possibly a vacuum leak on the driver's side?

An intake valve sticking intermittently, allowing an ignited fuel-air mixture to backfire through a poorly sealed or damaged intake valve?

[flat6_musik]

Many times you will get a carb backfire while accelerating and the carb is leaning out (for whatever reason, there could be many).

[joelsplace]

Check the compression to make sure you don't have a valve too tight. Backing off the adjustment until it ticks almost never works unless you are absolutely certain the lifter is pumped up. It seems like more times than not valves get adjusted incorrectly and people end up on the forums asking questions about that
One labor intensive way you can test your valve adjustment is to back off all of them until they just start to tick and drive it that way. If it runs better your valves were too tight.