firing sequence ford 8n, side mount

Backfire is firing through the carburetor. This happens when the ignition fires on the top of the exhaust stroke, begining of the intake.

Afterfire is firing through the exhaust. Can be caused by the above, as well a fouled plug allowing ignitable mixture into the exhaust system. Frequently called backfire, but that really is the incorrect term.

Not knowing the history of the engine... "backfiring" is a meaningless term. Is it an intake backfire or exhaust backfire? They have different causes.

Did you fool with the carburetor at all? Have you pulled the plugs to see if they are getting wet with gas? Have you done a compression test? Did you fool with the cam/valve timing? Is the valve lash set correctly?

Engines are pretty simple beasts. All they need is compression, a properly timed valve train, a properly timed spark, and fuel. As far as fuel goes, the righer the better until you can get it to run then you can play with mixture but if you start it too lean you'll be putting pistons in it.

The finger method in the plug hole works well for two people but I usually stuff a small loose wad of paper towel in the hole and then watch it blow out.

You can drain the float bowl, make sure you have fresh gas in the tank, make sure the fuel filter is in place, and then try to start it. If not, then have someone else try to start it while you spray carb/choke cleaner directly into the carb throat (keep your face to the side). If the ignition system is right, it should start, if just briefly.

If it won't contunue to run or runs poorly, what's likely happening that there is dirt between the float needle and seat or the float level is seriously misadjusted. That's causing raw gas to dump into the carb body. That hole is suppsosed to be there, it's the body drain.

In that case, you will have to pull the carb apart. If it has not been rebuilt or you are not sure of its status, you might want to get a rebuild kit and go through it. Use B12 Chemtool to clean everything. The kit or service manual should have instructions. While it's not rocket science, if you have never done one then you might want to have someone who has watch over your shoulder. It's especially important to get the float level right.