[ModelAMitch]

Originally Posted by mcgarrett

Speaking from my own experience, my car had some fuel flow problems and would sometime starve for fuel which would cause it to backfire due to intermittent fuel flow while driving above 30 mph. Once I cleared the blockage and got the fuel flowing good again the backfire went away and the car ran normally. Backfiring can also be due to a failing condenser, broken wire under the point plate, etc. If your timing gear is new, I'd begin to check the items mentioned above along with checking your timing to be sure nothing has changed there

Ive had my tank off to clean the rust out of it, have cleaned my carb recently and I have an inline fuel filter I change frequently whenever it gets a bit of sediment in it. I don't think Ive reached 30mph since changing the timing gear haha. But I have had my distributor apart and have not changed any of those parts before. Im hoping to make it to winter time before rebuilding the distributor. But may need to earlier if backfiring persists.

Originally Posted by cavalierhome

Backfire can be cause by lack of fuel. check the entire fuel run from inside the tank to the carburetor, and then inside the carb at the filter and the float.

I had that happen because an extra gasket was stuck inside the small glass bowl filter.

If you get too many big backfires then your muffler will split open at the top where the seems are, and then you will get perpetual backfires. I had to replace my muffler because of backfires, but that turned out to be a good thing in the end.

If you are backfiring when coating down hill check your timing, you may be way advanced.

But really look for a leak in the exhaust. With the car running put you hand just above the muffler (if you have a heat shield along side the space), do you feel exhaust air? Replace the muffler.

These all happened to me.

Thank you for the advice, Im fairly certain the backfirings are happening from under the hood, but Ill let the car idle tonight and get my hands under and around the muffler to feel for exhaust leaks.

I did notice backfiring when Im off the gas and coasting down a hill, it could definitely be that my timing is too advance during this time. I will pay attention to where my lever is next time Im doing this. Thank you

Originally Posted by aermotor

I also had backfiring on deceleration and found that 1 full turn CCW on the GAV fixed it, runs in all other modes well. Forgot - does in or out lean or enrich? Does 1 full turn out sound correct? Or, do I have a jet issue?

CCW will enrich the mixture (add more fuel) I have my GAV almost a half turn out. I havent messed with it while Im driving, but while the cars idling if I turn it either way it starts to run funky and doesnt like it. Atleast at idle I think Ive found the sweet spot, although everyone says each Model A prefers a different GAV adjustment.