1947 Farmall M: Episode 24

Ken Christopherson

Well-known Member
Hey all! I just wanted to give you guys a link to Episode 24 of the '47 Farmall M. Seems as though I've got a slight 'hiccup' while running the tractor.. Maybe a carb adjustment? Haven't played too much with it yet, but boy this tractor sure has some good power when it has a GOOD cylinder head on it! Oil pressure stays up, and the tractor doesn't miss a beat (except for the slight hiccup).. Grab your popcorn everyone! I hope you enjoy!
1947 Farmall M Episode 24
 
Great job Ken! From one Minnesotan to another I'm happy it finally worked out. I also enjoy all your videos. Keep them coming.

Todd
 
Thanks, Todd! Now it is on to the '42 H Project. Picked up the magneto today. Next on the list is to order a manifold and carb kit.. From there I should be ready to try for fire!
 
Ken, my Farmhand tag was peeling up on one corner, I carefully cleaned it, and glued it back on, with with Seal-All, I think it will last another twenty years. But never seen a Farmhand like your before, mine is a F-10
 
Yes, this Farmhand is quite a rare loader. I have only seen about a half dozen or so. I managed to purchase the original sales brochure off of eBay a couple years ago. The model is listed as a 'Standard'. Quite an interesting leaflet in very good original condition.
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From 60 years of letter series and 3XX and 4XX tractors yours is fine. I would tube a little bt they do that muffler popping stuff all the time. Jim
 
I just see these videos of guys who don't have any coughing back whatsoever.. Giving literal meaning to the expression 'runs like a clock'.. I thought maybe it was a little unburnt fuel, but the tractor smokes zero (even when given a good pop of the throttle).. Has great power when starting in road gear.. Under load there is no coughing. Might just have to run it the way it is for a while. Maybe it will smooth out once the engine is wore in.
 
The ever-so-slight uneven idling with low speed and lean mixture is caused by the design of the intake manifold. The routing to cylinders one and four is longer than the two center cylinders. Normal
 
Mostly they will continue to do it. Make sure the centrifugal advance is working with a timing light, and tune the carb some. Be assured all is well. Jim
 
The one thing you could easily check is the automatic spark advance. I don't recall if you have battery ignition or magneto so I am going to ASSUME you have a battery ignition in good shape. I think you put a gasoline head on and I am sure you have 4 inch pistons. Now if they are flat head pistons, that makes your engine a 264 , same size as a Super M . And a super m uses a 30 degree spark advance at full throttle. Regular M used a 40 degree.

What usually takes place is the springs and weights get worn and the spark is over advanced at all lower speeds. If you set static timing at top dead center, the distributor may very well be advancing 6, 7 or maybe even 10 degrees at low idle. Then it may be say 20 degrees at half throttle. All of these are too far advanced and cause a rough running engine. It makes that slapping of the rain cap you are getting. I want a steady advance starting from very close to top dead center at low idle speed of maybe 5 or 6 hundred rpm and not reaching full advance until engine is running rated speed of 1450 rpm. High idle of 1595 rpm.

Also, the mark should not be jumping around with timing light if bushings in distributor is tight, weights and springs not worn out and also, at low rpm, camshaft end play moving back and forth due to wear in spacer under camshaft gear. On my own m that I went through, I filled the spark advance limiting hole in on a 40 degree distributor shaft and did some tweaking on the springs to get a total advance of 30 degrees. With a little math figuring the size of hole I actually hit it very close on first try and left it there.

Remember also, an engine will always run, shall we say less freely, NOT ACTUALLY LABORING, if timing is set properly. Over advanced spark engine run freer at no load but that is wrong for a loaded working engines. Automobile and trucks used a vacuum advance along with centrifical advance and that gave those engines dual control for loaded and no load, but farm tractor engines never used that.

Now, if by chance you are using a magneto, you are lucky it runs as smooth as it does. Spark is full advance all running speeds.
 
Pete,

I do have 4 inch, stepped head pistons with an 8060 Gas head.. Tractor has quite a bit of snort from what I have experienced so far, and under load runs extremely well. I get the popping/coughing only when sitting idle (usually under half throttle). By your description I guess maybe I should consider myself lucky? Lol. I am running a magneto (I do on all of my tractors).. I just like the ability to run without a battery if need be, and they are simple and reliable if maintained properly.

About the only thing I could do is try to retard/advance the spark on the magneto by turning it.. Or adjust the carb slightly. The mag trips just as the pulley timing mark passes the needle on the front cover, so that should be dead on. The carb was set to manual recommended specs, and fine tuned from there. Judging by others responses, though. I'll probably leave it be for now as it seems it is running very strong.
 
You can't set the mag retarded enough to do any good without ruining the starting position of impulse. IH had a special impulse coupling for when we put in fire crater pistons and used a magneto. It gave about a 22 degree spark advance. Weren't as smooth as battery ignition but advance was where it belonged for working the tractor. I personally would never pull a M hard for very long with a standard 35 degree magneto impulse, step head pistons and gasoline head. You will be running into severe detonation problems.
 

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