Super M

[Big Boar]

I have a Super M that has trouble shutting off. I put it in road gear and let out on the clutch to kill it. What can I do?

 

[the tractior vet]

I have a Super M that has trouble shutting off. I put it in road gear and let out on the clutch to kill it. What can I do?

Well ing timing set to high, spark plugs wrong heat range, ideal RPM way to high , running to hot . cheap gas burning to hot . Carbon build up . And maybe it just wants to keep on working .

 

[used red MN]

Well ing timing set to high, spark plugs wrong heat range, ideal RPM way to high , running to hot .

How can the ignition timing have anything to do with this? All spark ignition engines I’ve ever worked on shut off the spark to stop the engine.
Big Boar
Of the other items mentioned, engine idle speed to fast is the main cause of this. Make sure the throttle is forward as far as it goes when shutting it off. Carbon build up probably second in line.

 

[Jim Becker]

How can the ignition timing have anything to do with this? All spark ignition engines I’ve ever worked on shut off the spark to stop the engine.

I think excess timing advance or overly high heat range spark plugs can cause excessive heat, making the spark plugs act a lot like glow plugs.

 

[used red MN]

I think excess timing advance

If he just got done pulling the arse off of it for 15 minutes straight at normal operating temperature and went to shut it off almost immediately with no cool down period this might be a legitimate answer.

 

[wh]

Has it been converted to alternator? Possible backfeed to ignition. Ignition Switch possibly not completely opening when shut off?

 

[DanielW]

Has it been converted to alternator? Possible backfeed to ignition. Ignition Switch possibly not completely opening when shut off?

That was my first thought. Somehow back-feeding to the coil (or faulty switch). But I think we'd need a bit more info on what's meant by, 'trouble shutting off'. Does the kill switch seemingly do nothing? In which case I'd suspect a wiring/back-feeding issue. Or does it kind of try to die and sputter but still keep in firing away for a bit? In which case I'd suspect dieseling out - must be running pretty hot in the chamber/plugs somehow.

If a 12V conversion, did you happen to use one of the pre-made spade connectors for Delco alternators that come with a diode built in (something like picture below)? Half the ones you buy these days have the diode in the wrong way around, so you'll go to kill the engine and it'll just keep running. No big deal to cut the diode out and solder it in the proper way around - just a little irksome. But you'd want to check the direction to confirm that's the problem first.

 

[used red MN]

Has it been converted to alternator? Possible backfeed to ignition. Ignition Switch possibly not completely opening when shut off?

Good point!

 

[Jim.ME]

Giving a good history can often help find the causes.

Is this a tractor you have owned for a while? If so, has it always had this issue, or did it just develop?

If you recently purchased it was it this way when you purchased it?

Have you ever completely tuned it up?

 

[the tractior vet]

How can the ignition timing have anything to do with this? All spark ignition engines I’ve ever worked on shut off the spark to stop the engine.
Big Boar
Of the other items mentioned, engine idle speed to fast is the main cause of this. Make sure the throttle is forward as far as it goes when shutting it off. Carbon build up probably second in line.

to far advanced or to far retard can cause this . . You just have not worked on enough stuff yet . Back in the late 60's and early seventy's we fought this on FO MO CO cars and trucks with the dual vac dist. Seen it on tractors . wrong plugs like the D 21 can cause this . ideal to high . The I H tractors with the fuel shut off on the carbs that is what that was for as the gassers of the time ran hotter and any carbon build up would glow and evern with no spark they would not shut down So plug the main fuel jet . When ya turned the key on the pintel came full off the main jet and tractor ran . Cars and trucks from back in my day were also fussy about a high ideal and would suffer run on , sometimes coughing back thru the carb and cause a carb fire . Mo Pars were great about this on start up when ing timing was set a T D C that ya found on the big blocks as factory set . And made for vary hard starting since ya had to crank them like starting a turbin . Bump the ing timing up to 10 degrees BTDC and the lite off better then a Ford. Just don't let the AIR NANNY'S see ya do it His S/M also may have big pistons and higher compression ratios along with the OLD ing timing as who knows if some one stuffed and old M dist on it with the 40 degree advance . SO with out putting a light to it we don't know the WHOLE STORY .

 

[MeanGene1]

In '78 I took my Galaxie over to Sears Point for the Wednesday Night Drags. It's a '62, and an original 406 engine car, but I had a 14:1 427 in it at the time, cross-ram intake, .660 cam, 40 degrees timing, 12 in slicks and 5.14 gears and loud like only a 427 Ford can be. Made one easy pass to make sure it was going to go straight, then came back and let it eat. 6000 off the line, almost... went up about 6 inches and the driveshaft went out the bottom. Hit the kill switch, but the hot 14:1 engine just kept running on, driveshaft going around clunk clunk. The starter is waving at me with the kill it signal, I'm trying, man, it won't quit running on. I finally pumped the gas a couple times and it quit. Yeah, lots of things will make a gas engine run-on with the ignition off lol

 

[used red MN]

Yeah, lots of things will make a gas engine run-on with the ignition off lol

Yep, I agree.. once the ignition is off the timing CANNOT be the source of the “run on”- “dieseling” whatever you want to call it. That dude telling me “I haven’t worked on enough stuff yet” doesn’t mean he’s the smartest. I don’t know in what condition an engine is “ideal”..strange that “idle” seems to interchange well with it.

 

[MeanGene1]

Yep, I agree.. once the ignition is off the timing CANNOT be the source of the “run on”- “dieseling” whatever you want to call it. That dude telling me “I haven’t worked on enough stuff yet” doesn’t mean he’s the smartest. I don’t know in what condition an engine is “ideal”..strange that “idle” seems to interchange well with it.

Well, he is pretty smart, and he has worlds of experience- and he's right. He's trying to help by sharing his knowledge and experience- maybe you should listen a little more

 

[used red MN]

Oops

 

[used red MN]

Yeah, lots of things will make a gas engine run-on with the ignition off lol

Well, he is pretty smart, and he has worlds of experience- and he's right. He's trying to help by sharing his knowledge and experience- maybe you should listen a little more

Seems odd to me that you agree with the item I say is not the cause of run on, yet you say he is right. I know this is an argument I can’t win in this ring, so I’ll drop it. Don’t want to knock his wobbly leg out from under him.

 

[Mark EC.IN]

Seems odd to me that you agree with the item I say is not the cause of run on, yet you say he is right. I know this is an argument I can’t win in this ring, so I’ll drop it. Don’t want to knock his wobbly leg out from under him

Having the timing too far advanced is probably the number one reason for "dieseling" in these old tractors. It makes the engine run hotter and creates hot spots in the cylinders. It's why they call it dieseling, it's firing without any spark.

 

[used red MN]

Mark in EC.IN said in reply to used red MN
“Having the timing too far advanced is probably the number one reason for "dieseling" in these old tractors. It makes the engine run hotter and creates hot spots in the cylinders. It's why they call it dieseling, it's firing without any spark.”

Okay, then have this guy do an experiment. Set his timing back 10 degrees and touch nothing else and then see if his “run-on” problem stops. It won’t!

 

[J.Wondergem]

to far advanced or to far retard can cause this . . You just have not worked on enough stuff yet . Back in the late 60's and early seventy's we fought this on FO MO CO cars and trucks with the dual vac dist. Seen it on tractors . wrong plugs like the D 21 can cause this . ideal to high . The I H tractors with the fuel shut off on the carbs that is what that was for as the gassers of the time ran hotter and any carbon build up would glow and evern with no spark they would not shut down So plug the main fuel jet . When ya turned the key on the pintel came full off the main jet and tractor ran . Cars and trucks from back in my day were also fussy about a high ideal and would suffer run on , sometimes coughing back thru the carb and cause a carb fire . Mo Pars were great about this on start up when ing timing was set a T D C that ya found on the big blocks as factory set . And made for vary hard starting since ya had to crank them like starting a turbin . Bump the ing timing up to 10 degrees BTDC and the lite off better then a Ford. Just don't let the AIR NANNY'S see ya do it His S/M also may have big pistons and higher compression ratios along with the OLD ing timing as who knows if some one stuffed and old M dist on it with the 40 degree advance . SO with out putting a light to it we don't know the WHOLE STORY .

I agree with vet. I had that on my stock car, retarded too much, run hot shut it off and it would diesel for a half minute or so.

 

[used red MN]

I’ll give you some answers and believe me everything I say is going to apply to an engine “dieseling” or “running on”.. not how “back in the day” the timing affected how some car reacted on start up. I worked on cars in the 80s/90s and worked on cars from the 60s and 70s I know what the TV is talking about, but we’re trying to give info that fixes the problem with this guys tractor.
First it would be nice to get some feed back from the OP to make sure his problem is not related to a botched alternator install and not a “compression type” run on problem at all. Then some info on the build of his engine and if it is a fresh rebuild or if it is long in the tooth possibly burning a little oil.
Seeing if it is idling at 450 or less is the number 1 thing to fix this. One thing that these old Farmalls do if they have been cranked up to run a higher full throttle rpm than stock is when the engine is shut off and slows down the governor opens the throttle plate. If the throttle linkage is worn setting it to run the high rpm with the wear when you pull it back to idle it no longer pulls the lever on the governor back enough to eliminate the governor opening the throttle at shut off. If need be he will have to open the angled plate with the vent tube above the governor and see if this is his problem by watching it during shut off.
Another thing he might need to do is to de-carbon his engine. For this you can use ATF or water or a combination of them. Pull the air tube off the carb and run it 1/2 throttle or more. Then with ATF dribble about a pencil lead sized stream into the air stream going in the carb run about a pint in it. When your pint is about gone pour faster to the point of where it doesn’t quite take it all. Then shut it off and let it set 4 hours or overnight is best. If you use water pour it in at about the same rate as a pee stream flooding it at the end as I described above with the ATF. An if your doing the water make sure it is at operating temperature when you do it, the ATF method is less dependent on engine temp. If you got a pretty paint job you”ll probably want to cover it with some old sheets or plastic because all manner of crap is going to come out of the exhaust. Also if there is really a lot of carbon in it it may not restart without pulling the plugs spraying them with carb cleaner and blasting them with compressed air.
After he tries the above we’ll see how it responds.