Why does carb bnackfire and catch on fire?

Question

Just replaced heads, intake, cam, lifters, etc., car won't start, and backfires through the carb and then flames.

I figure it to be timing but other than that I am lost. Any help would be appreciated.

Answer 1

Your timing belt/chain is not on correctly. Line up the marks on the pulleys like they should be.

Answer 2

Defo the timing . also check you have the plug leads in the correct order as that can cause a misfire & also check the inlet manifold is tight as this can cause a popping sound when you are trying to fire the car up ! i would say 70% of car`s firing order is 1342 . post more details of the car and i can give you more info !

Answer 3

will timing is your problem but a norther thing that will make a carb back fire is carbon on the valves win the motor is hot the carbon will get so hot on the valves that it will ignite the incoming charge of fuel and air. but you have got a timing problem or you have got one of your rockers set to tight check your timing and if it on check the rocker and make shear that one is not set to tight and not letting the valve close good luck

Answer 4

timing.also check float in carb and needle valve..start from begining...is dist in or 180 degrees out??..are valves too loose or tight???..are the pluf wires[fireing order] correct?? i once spent 3 days with a new backfiring engine.....dist was 2 plugs off.

Answer 5

Valve clearance too tight and not seating?
Do a compression test on each cylinder to find out which one is problematic.

What kind of engine.
SB Chevy w/hydr. lifters?

Answer 6

Your right it is the timing. The distributor may be 180* out.

Answer 7

I would say timing also.