Backfire

[Daves55Courier]

223 engine was running great, then suddenly backfired for the remaining 20 miles to home. I took off the distributor cap. Both advance return springs are still attached and the vac advance actuator arm is still attached to the breaker plate. I disconnected the hose from the vac advance and hooked up a MityVac. The vac advance is working properly with the MityVac. Can something be broken inside the carburator causing this.
Engine still idles smoothly, but backfiring begins any time you try to accellerate.
Any ideas ???

 

[flatford6]

Tight intake valve adjustment, exhaust valve barely opening, hot piece of carbon causing pre ignition like a glow plug, lean condition caused by lack of fuel such as partially plugged main jet or low fuel level from failing fuel pump, advanced ignition timing, spark jumping from one wire to another or inside of dist cap. Check the plugs for carbon deposits first.

 

[Anonymous]

Hello I am new but it Sounds like it could be your timing chain jumped a tooth. I run a 223 in my 61 unibody f100.

 

[Daves55Courier]

There appears to be an unusual amount of silvery powder buildup thrown around inside the distributor and all around underside of distributor cap I have never seen before. Its a new distributor. I cant tell where it is coming from. It is like very fine metal filings (powder fine). Could this be causing spark to jump between the towers on the inside ? What would cause this suddenly?
I'm going to get a magnifying glass and try to see if I can find the source of this.

 

[matt1967]

There appears to be an unusual amount of silvery powder buildup thrown around inside the distributor and all around underside of distributor cap I have never seen before. Its a new distributor. I cant tell where it is coming from. It is like very fine metal filings (powder fine). Could this be causing spark to jump between the towers on the inside ? What would cause this suddenly?
I'm going to get a magnifying glass and try to see if I can find the source of this.

carbon tracing. your firing the wrong cylinders at the wrong times under load. replace distributor cap, it likely has a crack.

 

[Daves55Courier]

I cleaned out the underside of the distributor cap with using a soft cloth soaked in mineral spirits and dried it. I used a shop vac to vacuum the fine powdery substance off the distributor breaker plate, put the cap back on and now there is no more backfiring.

 

[flatford6]

Is the silvery powder aluminum corrosion from water or is it fine aluminum grindings? If its grindings, it could be from the top bushing holding the distributor shaft. Better check the side play in the shaft. A drop of oil on it would probably cure the problem before it gets worse. If its a new distributor, it may not have been lubed when assembled. Or the rotor could be contacting one or more of the contacts on the cap due to the cap being missaligned on the housing. Good Luck

 

[Daves55Courier]

I believe it was very fine aluminum powder shavings. It vacuumed out easily with an old shop vac. I cannot detect any wear on the inner face of the tower contacts, nor the rotor. It is a new distributor. I added oil for the bushings till it ran out the trap door before installing the distributor in the engine, so its got plenty of oil. There doesnt seem to be any play in the shaft either. It runs fine now after cleaning it out and doesnt backfire, so I am just going to keep running it for now.