WD 45 back firing

[PA Jake]

I have a 1953 WD45 that started back firing. I check points gap,distributor cap for crack,timing all good.Check carb. and fuel supply to carb. also good. Any Ideas what else would cause the back firing.

 

[old]

If choking it helps it is running lean. If it doesn't help you could have a bad valve or need to adjust the valves

 

[Nordic]

If it backfires under load especially, it could be a weak coil. Please let us know when you find "the rat".

 

[PA Jake]

Thanks Old I will let you know what I find when Iget the valve cover off to check the ajustment, and if the ajustment is good I'll do a compresion test.

 

[tractorguy2]

My ford 641 will back fire, snap, and pop when its running out of gas.

 

[DrAllis]

How about four NEW spark plugs gapped to .025" ???? How about run a compression test BEFORE tearing off the valve cover ??? How about drain what gas you have, clean the sediment bowl and dump in a couple gallons of fresh gas that is water free???

 

[PA Jake]

To DR Allis. Spark plugs are new,new points and condensor,new wires,cleansd fuel bowl,cleaned and rebuilt carb flushed fuel tank,5 galons fresh fuel. I am more inclined to agree with OLD thatits valve related. It could be a valve that is sticking.

 

[Aaron SEIA]

If you did new points and condenser, try another condenser. Those things are junk more often than not right out of the box.
AaronSEIA

 

[Aaron SEIA]

Dr Allis's compression check would rule out valve train issues without tearing the tractor down too.
AaronSEIA

 

[PA Jake]

Not nessarily if it is a valve sticking open intermittently but if I pull the valve cover to check adjustment I can also see if a valve is sticking open. Also some times it runs fine and other times it does not. It will do it with no load or under load. Tried a little choke and doesn't help.Which tells me its getting enough fuel. Just so every body Knows I'm a retired auto Tech of 40 plus years. I know cars and trucks are not the same as tractors but the basics are the same.Fuel,spark timing.
.

 

[PA Jake]

Thanks to all who replied. I checked the valve adjustment and found to be right on, did a compression test and found to be 125 psi on all cylinders. The tractor was converted to 12v before I owned it. I found that it didn't have a resister for the alternator and no ballast for the ignition. After installing a ballast resister in feed wire to coil and 10 ohm 10 watt resister in alt. wire. I went to NAPA and got a tune up kit, which included points,condenser,rotor, and autolite plugs. After installing tractor now runs fine with no backfire. Again thanks to all who responded.

 

[old]

If it is a sticking valve you can try this trick to see if it helps. Mix 1 quart of ATF in 3 gal of gas a run it. That helps clean up the valves and also lubes them

 

[BUSHNELLMAN]

(quoted from post at 13:30:43 03/10/21) If it is a sticking valve you can try this trick to see if it helps. Mix 1 quart of ATF in 3 gal of gas a run it. That helps clean up the valves and also lubes them

I knew a guy that would run ATF in his gas every once a while, he added some to the oil shortly before changing ,convinced me that it was just high detergent oil. everything he worked on was pre 70's so...
Never seemed to cause any issues.
Hellava guy! Died after a bar fight at 67,good ole Snuffy