Wed Nov 14, 2012 9:52 pm
i was wondering if the governor on my 1947 farmall cub is working properly? how do they work, and how do you know if it failed. do these things operate like the governor on a small engine, when you put the engine under additional load, it opens the throttle plate on the carburetor. im guessing they have spinning weights? when i put the tractor into 3rd gear from a dead stop it loads the engine down quite a bit until its moving. i have to feather the clutch quite a bit when starting in 3rd gear from a stop. i know these tractors arent the most powerful machines on the planet but i just wondered what is considered normal. does "feathering" the clutch a little cause the clutch to wear out faster, what is considered "ridding the clutch", because i dont want to do that. should the RPM drop significantly when in 3rd gear. my tractor runs good, does not smoke, and has good oil pressure, i just wondered what is normal for these machines, this is my first cub. these tractors arent like cub cadet, that probably have a higher power/weight ratio and do not drop much in RPM's when you let off the clutch. is there any adjustment that i can make to the governor that will open the throttle plate a little more when placed under a load?
Wed Nov 14, 2012 10:05 pm
What you describe is pretty normal. You only have a 10hp engine trying to move nearly a ton of steel in 3rd gear. Having to feather the clutch to get moving in 3rd is normal, how much depends on how well it is tuned, how worn, and how much load. Riding the clutch is when you keep your foot on it and pushed down a little to where the Throwout bearing is partly engaged all the time, and since a cub TO bearing is a graphite block that is hard on them.
Wed Nov 14, 2012 10:06 pm
Normal. 3rd is a "road gear". the cub may run good, but unless it is optimal, it can be exactly as you describe. I suggest a full tune up, most importantly, adjust your valve lash. It should approve your 3rd gear opperation.
To check your governor, stand beside the carb and pull on the throttle rod. It should pull back.
Wed Nov 14, 2012 10:24 pm
i might check the valve lash come spring, everything else is in decent shape. i removed a couple of spark plugs... fairly new with only normal deposits. checked cap and rotor, fairly new as well.
Thu Nov 15, 2012 3:49 am
Full tuneup as Dale said checking everything, small HP so every little bit helps like adjusting the valves. Run some Seafoam through it to clean the valves and piston deposits. Check the compression after all of this to see what the numbers show. Even placing a timing light on it to make sure the distributor advance is working will help. Use the light, rev the engine while watching the mark advance on the front pulley. You would be amazed at how many advances are not working at all on theses little tractors.
Thu Nov 15, 2012 6:44 am
There is an adjustment for the governor: Set the speed lever to half way. Unhook the governor rod that runs from the carb to the governor, open the carb to full and readjust the end plate to fit, plus one additional turn. Can make a huge difference if it is not properly adjusted. Should be re-adjusted each time the carb is removed.
Thu Nov 15, 2012 7:07 am
The Cub has a very good governor when it is set up properly. As others have said you must recognize the hp limits of the engine. You can not just pop the clutch and expect the governor to respond. You have to give the governor time to recognize the load and respond. You do this by easing the clutch out slowly until the governor opens the throttle. If this is done properly, it should be a smooth operation without jerks or stalls. The governor will not be activated until the throttle is at a third to half open. Then, you should hear the engine trying to maintain set rpm as load is applied. You can also observe the increased engine exhaust output by watching the muffler cap pivot more open as the governor opens the carburetor throttle plate.
Thu Nov 15, 2012 7:09 am
Also, make sure your governor linkage is moving freely. Lubricate to rock shaft pivot, at the left front of the engine, and make sure the linkage rod is not rubbing anywhere. Yes the governor has weights, which constantly work against the external spring located at the top of the governor. Proper linkage adjustment is essential for the governor to function in a responsive, yet smooth manner.
Thu Nov 15, 2012 7:12 am
what operates the advance? i didnt know these tractors had any method of advancing timing. i have work on a few chevy small block V8 engines and on them you either have the computer adjusting the advance or a vacuum driven advanced; and when you adjust the distributor the computer OR the vacuum line must be disconnected in order for you adjustments to work. my tractor has the magneto style ignition. by adjusting the "plate" do you mean the rod that attaches the governor to the carburetor?
Thu Nov 15, 2012 8:34 am
Actually, with your magneto, there is no advance, in the normal thinking. The mag incorporates an impulse coupling which retards timing during engine start (to top dead center) and as soon as the engine starts, the impulse deactivates and the ignition timing advances and runs at 16deg. advance. Yogi's comment was assuming battery ignition.
Thu Nov 15, 2012 9:05 am
so on a cub that someone replaced the mag with a coil and kept the mag distributor no longer has the benefits of having the tractor having ability to advance timing. i have a timing light that i bought to use with my 350 v8 can i use the same timing light or will it not work due to the cub having a 6 volt system?
Thu Nov 15, 2012 9:17 am
ad356 wrote:so on a cub that someone replaced the mag with a coil and kept the mag distributor no longer has the benefits of having the tractor having ability to advance timing. i have a timing light that i bought to use with my 350 v8 can i use the same timing light or will it not work due to the cub having a 6 volt system?
Connect it to a 12v and it will work. Just pull your truck/car close if cables are long enough.
Thu Nov 15, 2012 9:54 am
If your timing light has the adjustable advance feature, it will work for a magneto, but if it does not, you will get an incorrect reading since the crankshaft pulley that came with the magneto equipped tractors only had a single mark at TDC, not one for the 16 degree advance. According to the manuals the magnetos only advanced 13 degrees, but checking them I have seen all the way from 13 degrees to 20 degrees. If your timing light does not have the advance feature you can mark the pulley at slightly over 21/32 inch before the TDC mark to adjust it. The main thing with a mag is to make sure it snaps at TDC when turning slowly with a hand crank. If it trips sooner it will tend to kick back and make it hard for the starter to crank, or hurt your hand if you are cranking. If it is late you will have low power.
Thu Nov 15, 2012 10:24 am
ad356 wrote:so on a cub that someone replaced the mag with a coil and kept the mag distributor no longer has the benefits of having the tractor having ability to advance timing.
The addition of an external coil to a magneto was an inexpensive fix when the magneto's internal coil failed.
Tractor is a 1947 year. Originally had a magneto, but the magneto could have been removed and a battery powered ignition system installed. There are photos of both the magneto and battery powered ignition systems in the operator's manual. Photos can be found on this site of magnetos with the external coil.
i have to feather the clutch quite a bit when starting in 3rd gear from a stop.
As previously suggested, conduct a 100% tune up including compression tests. Guessing you will find the compression on the low side.
What is the history of this Cub?
Thu Nov 15, 2012 11:23 am
i dont know the full history of my tractor, but it doesnt show signs of being worn out. i has good oil pressure, doesn't consume oil, and doesn't smoke or knock. i pulled a couple plugs.... no oil on the electrode only normal deposits. i assume that if it was worn out it would have poor oil pressure and it would probably burn oil. my tractor has the proper magneto coil. i just wondered what would happen if you replaced the magneto coil with a battery ignition coil
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