Farmall M - fuel or timing problem

[Justintime]

The low down. 49 M with 4" firecrater pistons, new rings, new valves, electronic igntion on original distributor, new springs on dist. weights (HEI lightweight springs), carb has been cleaned and has a #29 venturi in it, jets have not been touched (yet), air intake straight off of carb. Tractor starts and idles beautifully. The problem is that when I crack the throttle open to 3/4 or more it wants to stall or backfire, same when I put load on it. Pulling the choke does save it but it might take 2 pulls. Starting out it 5th also produces this backfire. I have adjusted the timing both in advance and retard. Is this a fuel or spark issue, what can be done?

 

[Dblair]

put a 25 venturi back in her

 

[Mike Bock]

sounds like fuel problem to me did you set fuel load jet under load,when you pull do you yank on throttle real fast,our does load of sled come on gradualy you are not drag racing are you

 

[Anonymous-0]

I would put a stiffer spring in Distributor.
Then I would start working on the jet end of things.
But thats me

 

[Anonymous-0]

I agree with stiff springs if the distributor has been identified as a 40 degree. If it has a 25 degree or less, then the light springs will help.

40 degree setups with light springs have caused backfiring and erratic timing as the mechanical advance operates. Just way too much travel in the advance for the throttle responce, and rpm,, or the whole engine in fact,,,,,,,,

Look at it like this,,, example:

Base timing at 25. then add the additional 40 degree advance equals 65 degrees worth of timing changes.

My opinion is you want the base timing, and the advance to total no more than 35 to 40 MAX.

It does need rejetted if the jet measures less than .100. It might be around .050 stock,,,,,,,,,

ChadS

 

[Anonymous-0]

25 for base is quite a bit isn't it? Granted I am running smaller stuff but they like 8 or 10 for a base and maybe Max out at 22 depending on the rpm.

 

[Justintime]

CHADS - what is the best way to identify which distributor this unit has? As far as I can tell it is the orignal.

 

[CJ_1080]

Too big of a venturi! If its mostly a stock rebuild, stick with a 25. If it is stroked, cammed, head changed or shaved, ect.... Then change the venturi. It doesnt take much venturi size to make a big difference.

 

[Anonymous-0]

The dead giveaway is when you pull the distributor cap off, then snap the rotor with your fingers,,, if the rotor travels almost to the next pole,,, its a 40.

Other than that description, you will have to pull it apart,,, there are two digits stamped into the advance plate, you can see it once the advance is removed. 40L is what you will see if its a 40,,,, Ive seen 15, 20, 22, 25, 30, 32 35 and 40 degree distributors, look for a 15 or a 20 and it will help. Chad

 

[Charles E. McNelly]

Put a timing light on it. I have the same setup except I still have the 3 7/8" pistons on mine and the 29 venturi helped me. What fuel are you running? What"s your total timing set at? What plugs are you using? Are you sure your not too lean? Blast me an email.
Charles

 

[Anonymous-0]

Fuel level in carb bowl could be low.

 

[Justintime]

Thank you for your help. I am questioning the venturi, and my next step was going to be go back to the 25. As for the dist. I will make that change if needed. It just seems like this tractor falls on its face when I try to pull it down. Thank you again.

 

[Justintime]

I have put a timing light on it but it does not have degree display. I would guess about 25 degrees advance. I am just using regular 87 octane unleaded fuel (no pinging). I have Autolites in right now but am open to suggestions. I do believe it is too lean, because I can back the fuel screw out almost all the way and still do not flood or smoke.

 

[CJ_1080]

One reason for that could be the lack of vaccum due to the larger venturi. It can't suck any more fuel. The reason it falls flat on its face is cause the air/fuel mixture isn't moving fast enough and you loose to many rpms to fast. Put in a 25 and watch what happens when you lug her down! Then play with your timing. Not knocking anyone else or there suggestions as there was some good ones. I had a H that acted the same way. You learn quick when you are prety good at screwing up your stuff! I am a very quick learner!!!!

 

[JUSTIN TIME]

THANK YOU. THAT IS MY NEXT STEP.

 

[awfulallen]

I just got my father's IH 656 tractor back from ChadS on Wednesday and boy what a mess! He had it for almost 3 months and had almost destroyed it. When we picked it up it was in pieces and they were spread everywhere, the floor, the footpads, buckets sitting around! I'm still not sure we got all of it! I urged my dad to recheck what little Chad had done and we found to name a few items; broken bolt in pressure plate (new clutch), old torn gaskets....when Chad removed the oil filter housing and govenor housing he just bolted them on the new motor! Didn't even clean off the old gaskets! We found dirt in the block, loose bolts, STRIPPED threads from over tightening! It was insane!

All I can say is he is not his father.......

If anyone wants more info please email me or find my dad at the tractor pulls......

Awful

 

[awfulallen]

(quoted from post at 18:32:09 06/05/10) I just got my father's IH 656 tractor back from ChadS on Wednesday and boy what a mess! He had it for almost 3 months and had almost destroyed it. When we picked it up it was in pieces and they were spread everywhere, the floor, the footpads, buckets sitting around! I'm still not sure we got all of it! I urged my dad to recheck what little Chad had done and we found to name a few items; broken bolt in pressure plate (new clutch), old torn gaskets....when Chad removed the oil filter housing and govenor housing he just bolted them on the new motor! Didn't even clean off the old gaskets! We found dirt in the block, loose bolts, STRIPPED threads from over tightening! It was insane!

All I can say is he is not his father.......

If anyone wants more info please email me or find my dad at the tractor pulls......

Awful

It was pointed out that my name was missing....

My name is Allen Kirkpatrick.....my dad is Bill Kirkpatrick.

 

[JUSTIN TIME]

THANKS FOR YOUR HELP. I HAD A CHANCE TO GET THE #25 BACK IN AND THE OLD M RUNS LIKE A CHAMP. THE ADVANCE IS WORKING AS IT SHOULD AND I CAN PUT SOME LOAD ON THE TRACTOR (BRAKES/AND STEEP HILL) AND IT PULLS ON THROUGH. IT DOES NOT SPUTTER OR BELCH WHEN THE THROTTLE IS PULLED. I AM GOING PUT IT ON THE DYNO SHORTLY AND HOPEFULLY GET A DECENT HP READING.