Trator backfiring

[resden]

What should be a plan of attack to stop a tractor from backfiring through the carburetor?

 

[Bob]

Give us a little more info!

Does it start and run?

When does it "backfire"?

All the time?

While attempting to start?

At idle?

While accelerating?

While at WOT?

Only when under load?

Or?

 

[old]

What tractor since that can make a difference at times. That can be as simple as the carb set/running to lean. Or a timing issue or a valve issue. Timing to advanced can cause that as will a valve that does not close up all the way due to carbon build up or sticking or tappet set to tight

 

[warren woodrow]

These guys know more than I but my experience is : timing off, sticky valve,and believe it or not a bad ground connection from battery to ground .
Still have not figured out why corroded ground cable caused it .

 

[David G]

When did this start?

 

[rustred]

check the compression. then report the readings FIRST THING to do on any engine. and the most neglected.

 

[David G]

How can you make that statement without knowing the conditions of the backfire?

 

[kevinj54]

(quoted from post at 16:28:32 01/12/19) What tractor since that can make a difference at times. That can be as simple as the carb set/running to lean. Or a timing issue or a valve issue. Timing to advanced can cause that as will a valve that does not close up all the way due to carbon build up or sticking or tappet set to tight

Don't forget 2 crossed wires or a cracked cap.

 

[rustred]

you asking me? what statement? it is obviously a valve or valve train problem, so naturally a compression check is the first thing to do. that gives you the engines condition. even when spark plugs are changed good idea to run a compression check . no where did it say it was done and from reading this it just started to backfire. cant see wires changing cyl's by them self. problem is a person has to read between the lines lots of times because of little info given. compression checking and reading spark plugs gives lots of info.

 

[Bob]

(quoted from post at 21:11:03 01/12/19) you asking me? what statement? it is obviously a valve or valve train problem, so naturally a compression check is the first thing to do. that gives you the engines condition. even when spark plugs are changed good idea to run a compression check . no where did it say it was done and from reading this it just started to backfire. cant see wires changing cyl's by them self. problem is a person has to read between the lines lots of times because of little info given. compression checking and reading spark plugs gives lots of info.

" problem is a person has to read between the lines lots of times because of little info given. "

Actually, there's another option, to do as I did and request more info, and wait for the O.P. to provide it.

We don't have (well, SOME of us at least) crystal balls and we're not paid to GUESS blindly!

 

[resden]

Sorry guys! Although I am a Farmall guy, this tractor is an Allis D19 gas. Engine was overhauled less than 50 hours ago.
Compression is 160 psi on all 6 cylinders, carb has been cleaned with a new kit, new plugs,wires,points,condensor, coil. Fuel
system has been cleaned and have good fuel flow to carb. Tractor sat in a shed and was not run for three years prior to me getting
it. Can only get it to start with full choke but then it misses, smokes, backfires, and stalls and will stop as soon as the choke
is released. Occasionally, it will run nice for 15 seconds which puzzles me. Gut is telling me to recheck ignition system, check
manifold gasket, etc. But thought you guys might have some other ideas!

 

[kevinj54]

(quoted from post at 09:42:25 01/13/19) Sorry guys! Although I am a Farmall guy, this tractor is an Allis D19 gas.

Not sure what this means as they all work the same way.

It sounds like you did not do the carb right or it would not need full choke to run.

 

[rustyfarmall]

(quoted from post at 06:42:25 01/13/19) Sorry guys! Although I am a Farmall guy, this tractor is an Allis D19 gas. Engine was overhauled less than 50 hours ago.
Compression is 160 psi on all 6 cylinders, carb has been cleaned with a new kit, new plugs,wires,points,condensor, coil. Fuel
system has been cleaned and have good fuel flow to carb. Tractor sat in a shed and was not run for three years prior to me getting
it. Can only get it to start with full choke but then it misses, smokes, backfires, and stalls and will stop as soon as the choke
is released. Occasionally, it will run nice for 15 seconds which puzzles me. Gut is telling me to recheck ignition system, check
manifold gasket, etc. But thought you guys might have some other ideas!

If the tractor sat for 3 years, most likely the carburetor needs a good cleaning. Fuel problems and ignition problems will quite often mimic each other. Makes no difference if it is Allis-Chalmers or Farmall.

 

[rustred]

still unclear if you recently did this work or the tractor has sat for 3 years with that work done to it before it was parked??? do you know if it ran good before parking it?if it sat that long then the carb still will need a cleaning if it had gas sit in it. also the points will need a cleaning and check the gap. also the intake valve clearance is only .012 so I would be running a valve adjustment check also. that is a tight clearance and with the unexperienced guys can have two people with different settings doing the same adjustment. which means with a tight valve she wont run right. and have you checked the firing order (153624).also the distributor cap my have a crack,also this backfire your talking about is that through the carburetor? is it a backfire or an engine miss? an engine is an engine and when set to specification's they run pretty darn good with fuel and air and spark.

 

[F-Dean]

Check the order and direction of the spark plug wires - clockwise vs counter-clockwise.
The correct order but in the wrong direction will cause 2 cylinders to fire at the correct time and 2 to backfire.
Yes, this is from experience!