BACKFIREING

JEFF NC · Jan 20, 2011

I HAVE A 47 H FARMALL THAT IS BACKFIREING THROUGH THE CARB. I HAVE TIMED THE MAG AND REPLACED 6 VOLT BATTERY AND CHANGED THE WIRES AND PLUGS.I ALSO REBUILT THE HEAD WITH NEW VALVES AND ADJUSTED THEM. I ALSO REBUILT THE CARB. THE TRACTOR STARTS GOOD BUT HAS THE BACKFIREING POP IN THE BREATHER. IT WILL PULL IN ALL THE GEARS ALSO. ANY ADVISE IS APPRECIATED.

old · Jan 20, 2011

A back fire like that a lot of times is caused by the engine running way to lean. #1 check and clean the air cleaner and make sure it has good oil in it etc. #2 open up the main jet a little at a time to see if that helps. One way to double check this is to coke it some and if when you choke it some it stops you know 100% sure it is running lean

MisterT · Jan 20, 2011

Double check that the plug wires are in the correct firing order, and then double check the valve clearance adjustment. Set the valve gap at 0.020" with the engine cold.

cody bodiford · Jan 20, 2011

hayy buddy i have seen before a push rod bein bent or lifter stuck and it has happend to me so that would be a place to check you have already checked the carb wire and aircleaner.....have any questions just email me at [email protected]

El Toro · Jan 20, 2011

What did you set the valves at? Open that main jet adjusting scr/w near the bottom of the carburetor. Your plug wires need to be in this firing order on the cap. Your battery doesn't supply voltage to a mag unless you converted it to a distributor. Hal

1-3
2-4 As the rotor turns CW

El Toro · Jan 20, 2011

That firing order is wrong it should be this: Hal

2-1
4-3

Tractor Carbs · Jan 20, 2011

HI- sounds lean if it will start and run, if it's lean it will pop through the carb , too rich it will pop out the exhaust pipe when throttling down. Try to adjust the main load screw out 1/8-1/4 turn at a time and even the idle mixture screw a bit to the right to add more fuel. One way to check the mixture is goose the throttle quick from idle to full and it should rev up quick with out coughing back through the carb. If timing and ignition system is good and you can't git rid of the cough you may have a small passage way, air bleed ect. in the carb restricted and need more work. Write back if you still have problems and I would be happy to help, tractor carburetors are my specialty - Dan.

F-Dean · Jan 21, 2011

Check that you have the firing order going in the correct rotation -- I believe it should be clockwise as seen from the driver's seat. Take the distributor cap off and turn it over to double-check.

An engine will run with a lot of back-firing if you have the wrong rotation -- two cyclinders will be firing at the right time.

Yes, this advice is based on experience!

JEFF NC · Jan 25, 2011

I HAVE A MANUEL FOR THE H AND IT SAYS THE FIREING ORDER IS 1 3 4 2. IS THIS NOT RIGHT? I DID SET THE VALVES AT 20,000. ALSO I HAVE ADJUSTED THE SCREWS ON THE CARB STARTING AT 1 AND A HALF TURNS OUT . THEN IN AND OUT. NOT MUCH DIFFERENCE IN THE WAY IT RUNS. IS IT POSSIBLE ITS NOT GETTING ENOUGH FUEL THROUGH THE LINE? IT SEEMS TO BE MOVING A LOT OF FUEL.

THANKS,

JEFF

JEFF NC · Jan 25, 2011

IT LOOKS LIKE THE LIFTERS ARE MOVEING UP AND DOWN WHEN IT IS RUNNING. I LOOKED AT THE RODS AND THEY LOOK STRAIGHT. IS THEIR ANOTHER WAY TO CHECK FOR STICKING LIFTERS OR A PROBLEM WITH RODS?

Thanks,

Jeff

BACKFIREING

JEFF NC

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old

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MisterT

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cody bodiford

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El Toro

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El Toro

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Tractor Carbs

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JEFF NC

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JEFF NC

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