Carburetor backfire??

[frolio2986]

I recently rebuilt the top end of my jeep: new pistons, rings, valves, reworked head. It runs but the carburetor hesitates upon acceleration and backfires often with flames. I have set the valves numerous times only with the same results. What would cause flames to come out of the carburetor?
It seems to me that for flames to come out of it, the plugs would have to spark while the intake valves are open, and that doesnt seem like it could happen. I know it could also be the intake valves not seating properly but i had the head reworked and the valves ground.

[jeepguyxj]

check your firing order maybe you got two wires backwardes. did that once and flames throught the carb. or timming problem. hope this helps

[supernova70]

I had that same problem with my nova.when you get a studder and a backfire that means your running to lean. you will most likely need to jet your carb up 1 jet at a time until the problem is fixed. very simple!takes 10 min. good luck

[MagicRat]

Originally Posted by supernova70

I had that same problem with my nova.when you get a studder and a backfire that means your running to lean. you will most likely need to jet your carb up 1 jet at a time until the problem is fixed. very simple!takes 10 min. good luck

It is running too lean, but its not the main jetting. Its the accelerator pump that is not working. It creates a lean condition in the intake manifold which makes the hesitation you feel.
This lean mixture can be ignited from an intake valve.
Fix the accelerator pump so it provides a bigger squirt of fuel when you step on the accelerator. Dont worry about the valves. The problem will go away when the pump is adjusted.

[supernova70]

good call magicrat,I forgot about that.frolio, check out what magicrat said first. if that doesn't work then check your jets. oh yeah, if your carb has float bowls, check those too.make sure the gas is no lower than the bottom of the port.