Exhaust backfire I have a 61 Vette with a new 350 crate. Backfiring only occurs when slowing down. Can't figure it out

After-market exhaust system or stock?

A lot of after-market mufflers don't cover up a backfire pop on over-run in the way that the stock system does. Look at The Marble Mod on GIXXER forums for ways to doctor the bike's emissions system to stop the popping.

Another cause of an over-run backfire may be a slight leak where the header pipes emerge from the cylinder head. Check the bolts are tight. Consider new copper washers.

This sounds like it is a fuel supply problem NOT an exhaust issue. It will be worth you getting a good garage to check the whole fuel system. "Back firing" is a loud bang caused by too much fuel passing all the way through the engine and exploding when it hits the hot exhaust. It is NOT very common in modern cars so get a good mechanic to check the car.

Your timing is off. Backfiring occurs because the exhaust valves are open when the fuel is combusting.

It could be the speed of one carburetor is faster than the other. This causes the backfiring as well as forces one cylinder to run lean which causes the tapping noise. You will experience an identical tapping or "ping" when you get close to empty on main fuel and need to switch to reserve. Most likely you or the previous owner unknowingly adjusted the speed of the rear carburetor down because of the high stock idle not realizing the front carburetor needs to be slowed down to match. While running simply turn the idle adjust screw clockwise on the rear carburetor until the idle smooths out and the backfiring/tapping stops.

Sounds like a vacuum leak in the motor. Backfiring may be its own problem altogether. Backfiring only occurs when cold air is being introduced into a hot exhaust stream or when the timing is off. Check for vacuum leaks under the hood and leaks in your exhaust. If you have a leak in your exhaust it could be interfearing with your emission sensors and giving your motor false information.

Two things cause this problem, ONE: Your timing could be out a little and the bike needs a good tune, or TWO: your exhaust is cactus.

You probably have a clogged up exhaust system building backpressure on the engine. Check your mufflers and catalytic convertors if you have them something is restricting the exhaust.

hi mate try changing the spark plug and its backfiring because you have to much fuel going into the barrel and all of the fuel is not being burnt so some is going into the exhaust and when you let off the throttle it backfires so on the carb there are 2 screws 1 for idle and 1 for mixture the mixture is the one you need screw it in 1/2 of turn at a time until it stops backfiring ok a picture will demonstrate

Check your head gaskets. And your exhaust gaskets, you have blew one of the gaskets your head gasket will leak oil and your oil will look milky and watery. Your exhaust you are going to have to take off and see

First define backfire - I know backfiring as a loud bang from the exhaust caused by unburned fuel entering the exhaust and combusting there. Some people refer to a spit-back through the intake as a backfire, the latter being caused usually by a slow burning lean mixture still burning when the intake valve opens. This mostly occurs when the throttle is opened allowing a rush of air without the addition of extra fuel but can also be caused by a poor or delayed spark.

Combustion in the exhaust is rare these days.