tempermentle m?

henryrit

Member
I've been having problems to get my m to pull hard under load, when the governer kicks in it will start to pull hard them start popping,but if you back off on the throttle and pull it back to wide open it will pull smooth any suggestions, it has a new dist. Electronic ignition, flamethrower coil.new plugs,wires, plugs are gaped at .30. The governor has a heavy spring in it.I've adjusted the valves, I has a 450 cam in it. It has 4" fire crater high dome pistons , and the jet in the carb is drilled out. The timing is set a tdc at idle to.the first notch. Thanks in advance,george
 
You didn"t mention if you saw any smoke of any color coming out when it does this. Usually, when an engine starts popping when the carb is opened up, it indicates a lean condition as a flooding condition as a rule of thumb, doesn"t make a pop or backfire. I had a John Deere that when it was put under high stress, would begin to snap and pop and I eventually found out that the octane of the fuel wasn"t high enough and it was detonating. You might try some higher octane and see if helps.
 
Sorry,I get some black smoke when its idling and about half throttle.but under load im not really smoking much at all.and I've run an advancing timing light on it at full throttle and its advancing 25 degrees,when it does it, it almost acts like it running out of fuel.
 
make sure the petronix is firmly bolted to the points plate. ive seen em come loose n create that issue. also check your ign switch and wires. could have a bad switch or broken wire.
 
sounds right. But usually if you move the throttle and governor, it will come back pretty fast. set your low speed carb adjustment to help the smoke at idle and part throttle. If it has a high speed adjustment screw, open it about 1/2 turn but most likely it will be a fixed jet inside the carb and to richen the wot usage, a jet replacement is necessary.
 
You haven"t done much to the engine. I would pull all of the plugs and look at the color of them and check the compression in all they cylnders and make sure it is good and close together. Then I would check the valve adjustment. Check the Intake for leaks and check the timing at full advance. I own a dyno. I would put it on the dyno and set the carb to where it makes the most power at 540 rpms by adjusting timeing and the carb. The dyno will help you get it correct when it is under a load. The wiring is simple and so is the egnition. Its got to be something simple. Start with the basics and go from there.
 
The plugs are alittle black but the electrodes are a light tannish color, the compression is from 1 to 4, 135,134,134 and 135psi. I had it tuned in on a dyno last year ,but since I changed the cam and had to put a head gasket in it ,my buddy sold his dyno ( for $500 dollars and didn't even let me know.cause I would have bought it). I haven't been able to get it right, if I don't back the throttle.down when it starts its popping fast enough it will almost die right out like its outta gas. But I can let off on the throttle for a second and pull it wide open it will pull hard and lug but will eventually start its popping again in about 20 to thirty feet.
 
I also had a new bushing put in the dist. And put the electronic ignition in it. And the guy that put the bushing in it changed the advance springs cause he said they where stretched out.
 
the nebraska test for a sm says it needs 3.9 gallons per hr. to get 47 hp . pull the plug on the bottom and make sure it gets that amount through the carburetor
 
This is a long shot, did you happen to put a larger venturi in the carburetor?

On car and motorcycle engines, when an engine is "over-carbureted" it can run lean at low air flows (low rpm) and wide open throttle. When the throttle quickly moves to wide open at low RPM there isn't enough vacuum to pull fuel into the airstream until the RPMs rises. Accelerator pumps are used to squirt in extra fuel until vacuum builds again. A car's driver can ease the throttle open, but a tractor's governor can't do that.

Being over-carburation can also hurt low speed lugging torque.
 
You can tell listening to an M running wide open under a full load if it's getting enough fuel and tuned good...it will show wisps of black smoke and sound real "healthy". "Back in their day" I used to watch IH mechanics dyno Farmalls after they had put in high altitude or fire crater pistons and thin wall sleeves and that's how they set the power jet screw on the carburetors to get the power they were supposed to develop.....and a little more usually.
 
I did change the venture, but it was the same number it just looked like someone had polished it. I will pull out out and Mic It to make sure it's not bigger.never thought of that.
 
(quoted from post at 03:41:14 08/19/14) I've been having problems to get my m to pull hard under load, when the governer kicks in it will start to pull hard them start popping,but if you back off on the throttle and pull it back to wide open it will pull smooth any suggestions, it has a new dist. Electronic ignition, flamethrower coil.new plugs,wires, plugs are gaped at .30. The governor has a heavy spring in it.I've adjusted the valves, I has a 450 cam in it. It has 4" fire crater high dome pistons , and the jet in the carb is drilled out. The timing is set a tdc at idle to.the first notch. Thanks in advance,george

Try tightening the gap of your plugs to 0.020" first. If the problem goes away take them to 0.025 and see if it will run there.
 
So I just pulled the venture out and measured it and measured one that was outta a different carb and the one in my tractor is .030 bigger,both are 474Q7-D
 

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