[farmerk]

Truck had flames coming from tail pipe almost always backfired but it dident new starter spark plugs oil antifreeze

Just dont know

 

[Groundhawg]

Mine used to backfire through the exhuast too. Took catalytic converter off and it's never done it since. I think if it was the timing it would backfire through the carburetor.

 

[BrianT]

seems like the carb is running super rich . what carb u using on your rig anyhow ?

 

[Slanted_Mind]

You need to verify whether the timing chain has jumped or not.

Bring #1 to TDC compression
Take off distributor cap. Rotor should be pointed at #1 (or very close to it)
Look at your timing mark, it should read zero. If it is way off, either your timing chain has jumped, or the outer casing on the dampener has slipped. Only way to verify the chain over the dampener case slipping at this step is to remove the valve cover and verify that both #1 intake and #1 exhaust valves are closed (zero lift).

Once you verify the chain, I would start looking at 'normal' timing issues and fuel delivery. An extreme rich condition should just blow lots of black smoke from the pipes. Timing causes backfires (or possibly weak or malfuntioning ignition)

-SM