Carburetor Difference

[fillupd]

I drove around for awhile today and when I shut my car off there was a really loud backfire out the exhaust. Could I assume my timing is off a little?
It seemed like it took about 1/2 second to bang out the pipe after shutdown.

[So Cal Mark]

that was unburned fuel, probably from an idle speed set too high

[fillupd]

I set the idle lower, maybe a little too low. Now it just bangs quieter. I'm going to install the new points and stuff tonight and try to tweak with the carburetor a little. I'm thinking maybe the air/fuel idle adjustment screw?
Update:
All new ignition stuff, new carb adjusted, wax job, runs great: Me Happy !