Reply to "Backfiring engine..."

Go to basics first. There are only two reasons an engine like yours won't run.

1) not getting fuel or 2) ignition not firing.

First pull a spark plug wire from a plug. Pull back the rubber spark plug insulation from the internal plug connector. Brace it so it is close to a chassis ground. Maybe a bolt on the intake manifold. Then fire the engine and observe to see if the wire is grounding out.

If it is, reconnect it to the plug and go to the carb.

Take off the air cleaner. Climb in the engine compartment so that you can see down the throat of the carb clearly. Observe the choke flap.

Is it open or closed? Does it move freely with your finger?

Hold open the choke, look down the throat of the carb, operate the throttle. Does fuel squirt from the "accellerator jets?

If everything is good so far, if it is a Holley carb get some rags and place them under the fuel level screws on the sides of the fuel bowls.

You need a wide slotted screwdriver. Open the front one first. Ideally, the fuel level will be right at the edge of the hole. If it pours out and is obviously above the top of the hole, expect that the carb is likely flooding and look for the cause. Most likely will be debris between the float valve and its seat. You will need to disassemble the carb to clear it.

If this is a Holley carb, the original brass floats are know to fail and collapse. The current blend of ethanol in todays gasolene, accellerates that failure since the ethanol will slowly errode the brass floats away and they will fail with absolutely no warning.

If you haven't replaced the floats with plastic foam ones, then you should do that now also.

The safest thing to do is to replace the float inlet valves.

You can repeat this for the rear.

If the fuel bowls are empty or almost empty, expect a blocke fuel filter or even a blocked fuel pick up in the tank (since you said you saw rust flakes in the fuel).

These are the immediate treatments and if you get it running and it is still missing and/or running rough then it can be any multitude of aliments from minor to serious requiring an engine rebuild.

I hope you problem is minor and easily repaired.