Farmall H high end miss

t martin · Feb 6, 2009

I have a 43 H that was just through the shop. Sleeves, pistons, head, crank, etc. The tractor is running now. It is fine at low and mid range but when opened up to full throttle and put under load it falls on its face. The main jet settings seem to have no effect on the problem but I know everything is clean in there. It has new points, condensor, cap, rotor, plugs wires, plugs, and coil. The points are gapped at .020. Any ideas as to what would cause this high rpm hiccup?

CNKS · Feb 6, 2009

Sounds like a lean mixture. Set wide open throttle, turn main jet screw in until rough, out until smooth plus about 1/4-1/2 turn. Do the idle the same way. Repeat as necessary until it will accelerate smoothly from idle to full rpm when throttle is moved rapidly from idle. Set timing by ear for max RPM. If that does not work and points are set at .020 and plugs at .023-.025, your carb is not completely clean, or you have a distributer problem, possibly worn shaft, etc.

Red Mist · Feb 6, 2009

In addition to what CNKS told you, you might also check your valve lash. .017" hot or about .020" cold.
mike

the tractor vet · Feb 6, 2009

When ya set the valves Just set them and be done with it because it is like this if you put the valve cover on and worked the tractor to get it HOT by the time you got it into the shop shut it down and pulled the valve cover back off and started resetting the valves she has already cooled down . Now if your working in the artic well then ya may want to WARM it up a bit

the tractor vet · Feb 6, 2009

Ah BUT did you set the engine timing ????? at wide open throttle ???? for total advance ???? nobody touched on that one . and as for the carb open it up 4 to 5 turns off the seat then if she smokes like a super stocker then back it down a little at a time to the point that you have good throttle response with just a light haze . SO put a timing lite on her and mark your timing notches with white paint and set it. If ya want it to run wright then do it wright as ya can not set up and engine just by ear no matter what someone will tell ya . In all the years that i have worked on all kinds of engines when it is a gasser it gets a timing lite put on it and if ya don't have one then buy one.

Anonymous-0 · Feb 6, 2009

Do like the Vet says and use a timing light. Timing by ear is a bunch of nonsense as everyone has a different ear.

Anonymous-0 · Feb 6, 2009

If the load jet has no effect on the problem the carb is NOT CLEAN, no matter what you know, you should be able to open the jet to the point that the engine is "flooding"; i.e. black smoke from exhaust just like it was choked.

Fixer · Feb 6, 2009

I think the best thing ever invented for this kind of thing, timing a engine. Is a dial back timing light. Just set the light where you want your max advance to be. Crank it up wide open should be right where you want it if its right at idle. more luck Bernie Steffen

Rollie NE PA · Feb 6, 2009

Hi, I bought an H that had been rebuilt and would not idle worth a darn but would run good under load and hi rpm. I found that the engine rebuilder had put in the wrong valves. If you can't solve your problem as others have suggested you might want to check and see if the right vaves were installed.
Good Luck, Rollie

Bob Kerr · Feb 6, 2009

If it was just rebuilt better go back and retorque the head and intake if that wasn't done. They should be re tightened after they warm up on first running. Readust the valves when HOT after torquing the head.

CNKS · Feb 6, 2009

They are very deaf if they can't pick the point where the rpm peaks, and I am deafer than most people. I don't use a light, and setting by the operator's or service manual (which don't use a light either), usually (not always) results in the engine acting lack it is under load. A slight movement of the distributer gets rid of that. If the engine does not ping under load, it doesn't hurt anything. The 4 cylinder IH letter series engines are not that sophisticated. But, I would not try that on the newer engines.

the tractor vet · Feb 6, 2009

Well just how many engines have you built in the last say 45 years that have run in comp. and how many trophies have you set on the mantle . How many S/MTA's have ya built that make over 75 HP or 706 gassers running with 806' diesels???? I think i know a little more about setting up a Farmall better the 95% of the people on here and any day that you think you can match your ear to a correctly timed engine we should get to gather and we will just have to put one on a DYNO and have at it . And i do not think that you can match me .

Wayne in MN · Feb 6, 2009

If you have an in-line fuel filter, get rid of it. You have either a restricted fuel supply or dirty high speed circuit in the carb.
Is the gas cap vent plugged?

charles todd · Feb 6, 2009

I agree with The Vet there CNKS. Proper ignition timing cannot be done by ear. I have seen those who have tried. They sound good, but run poorly when put under a true load (close to rated engine load). May it be a simple 4 cylinder engine, an inline 6 or a fire breathing V-8, put a light on it. An advanve type is not nessecary but is a nice feature. If ya do not have a timing light, buy one with the advance built in.

Back in HS a buddy had an 87 Dodge with a 230 slant 6. They tuned it by ear and at idle and at higher RPM's sounded dang good. If ya punched it going down the road it would fall on its face. Put the light on it and it was about 20 to 30 degrees out of spec... After putting the light on it the ol Dodge ran as good as a Dodge could

It was still a Dodge :lol:

Do not get me wrong CNKS, you bring a lot of good info to the Farmall and Paint boards. You are quite knowledgable, but one cannot properly time an engine by ear.

Charles

CGtractor · Feb 7, 2009

Sounds like most likely a fuel issue unless the timing is way off. You can slightly change timing while running to see if problems improve. I have been fooled many times by a freshly rebuilt carburetor. There are some small ports that can still be plugged in a "clean" carburetor. Let us know how it turns out.

Nebraska Cowman · Feb 7, 2009

I'd have to differ. You can time one by ear if you know what to listen for. And I was taught by another old man that timed by ear. But... Although I get along fine on 4 cylinder engines I never have been able to properly "hear" a 6 or 8 cylinder.

John M · Feb 7, 2009

I wouldnt try and argue with him CK. Hes going to be right, even when hes wrong.

Red Mist · Feb 7, 2009

(quoted from post at 19:57:48 02/06/09) If it was just rebuilt better go back and retorque the head and intake if that wasn't done. They should be re tightened after they warm up on first running. Readust the valves when HOT after torquing the head.

Yes - pay attention to what Bob Kerr said. There is a good chance you have an air leak somewhere , especially in view of the fact the engine was just put back together. In that case, all the carb adjusting in the world won't make much difference.
mike

CNKS · Feb 7, 2009

TV, I make no attempt to compete with you -- I just do what works for me. I drove an H as a teenager for about 5000 hours -- I don't remember if we ever even changed the timing. Then I left the farm for about 40 years. Don't use may tractors much, only a hobby, when I do they are not under full load. If they were, perhaps I would change my mind. I do have a lot of respect of your knowledge, you have been considerable help to me. But, I have zero respect for your bragging.

CNKS · Feb 7, 2009

Could be, I don't deny that a timing light will get it closer, whether there is any practical value over either static or ear timing PROVIDING the advance is working right, I don't know. I first set the static timing. If it runs ok, I leave it alone. (The operators/service manuals for the letter series do not mention timing lights.) If it seems to labor, I rotate the distributer until it is smooth. That works for me and does not harm the engine. As stated, I don't have a way (or need) to use full load on my 4 retirement acres. If they were work tractors, I would do whatever was necessary. And I do know what a smooth running engine sounds like, with or without my hearing aids. The method used to time older cars, before all the emission controls, seen in print many times, was to advance the timing, (using a timing light) until there was a very light short duration ping under full acceleration -- any more and the engine would not last long. As to tractors, those older tractors will literally tell you when something is wrong. But, I am currently working on a 460, you can bet that that one will get a timing light. I'm going to shut up now, I don't want to start arguing like Tractor Vet.

Farmall H high end miss

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