Why does my Model A backfire between shifts and after its off?

dynaflash_8

dynaflash_8

Member
So iv been driving the heck outta my 30 coupe. Over 300 miles so far in about 2 weeks. One thing i can not get rid of is the pop out the tailpipe between shifts. It doesnt do it when its cold, but after about 10 miles between shifts it has a loud backfire out the tailpipe. Seems to be worse when its retarded, but if i give it full advance, its not so bad. Also, if i drive the car for long distances, when i go to shut it off, it backfires out the tailpipe like a shotgun. :eek:This backfire occures 10 seconds after everything in the motor has stopped. Tonight it did this and blew the muffler off the car. :mad:

Iv done a full tune up, points rotor the whole bit, and tinkered with the carb, and it will not quit. What the heck is going on???
 
You will get a lot of advice on this one, but here are a couple of things to check.

1. Float level. Turn off the gas valve before shutting down and let it run out of
gas before turning off the switch. if it takes too long to stop, it probably means
that the float is too high.

2. Try driving with spark lever in different positions other than all the way up or
all the way down. You mentioned that it's worse when the lever is up. That is
normal, because you shouldn't be driving with it in the up (retarded) position.
I suggest your timing might be off. Each lever has its own "sweet spot" and you
have to find it. Mine likes it all the way down at highway speeds, and about 3/4
down if I am just crawling along at 10-15 mph. Also, don't forget to make sure
the throttle is all the way up when you shut off the engine. Good luck.

Jack
 
You can check your timing by retarding the spark lever, remove the distributor cap and body, turn on the ignition key (make sure your car is in neutral with E-Brake on). Press on the timing pin and slowly crank the engine until the pin sets into the timing gear recess. Do this while watching the points. At the exact moment the timing pin falls into the timing gear recess the points should spark. If not your timing is off. My guess is your timing is late
 
That shotgun blast 10 seconds after you turn off the engine - bad condenser. Easy and cheap fix.

Do you get popping from the tail pipe when you let off the gas at speed? If so, check your mixture, it is probably a shade too lean.
 
When I had the "shotgun blast" after turning off the ignition, I traced the problem to a bad fit between the exhaust manifold and the tailpipe. After tightening that connection I had no more problems.

It does make for an attention grabbing entrance when you arrive at your destination. When I had the Shotgun blast impression, it was time to shout "Shoot him in the pants the coat belongs to me".
 
I had a backfire issue until I put a brand-new shiney condenser in there...haven't had the problem since...but I still put my fingers in my ears immediately when I shut her down for at least 10 seconds!

Frank, where does that interesting quote come from you shout?
 
Frank, where does that interesting quote come from you shout?[/QUOTE]

I had an old buddy who would always say "Shoot em in the pants the coat belongs to me" any time he would hear a gun shot sound or back fire. I have no idea where the quote came from, but now that he has passed I always get a smile on my face when I have the occasion to use it and remember his humor.
 
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