Farmall Cub Forum
Sun Nov 18, 2012 7:27 am
My 49 Cub starts great all year long but now the cold weather has changed that. I have a good strong battery (6volt) and it spins fine. I have tried several different starting strategies to try to find one that works. but the only way I can get her to fire up is.
throttle 3/4, choke full, crank then choke to 1/2 and then grab the rod from the carb to the governor and pull it all the way forward, while cranking
that last part scares me. does that tell anyone anything that may be wrong or misadjusted. I dont think pulling the governor forward is good for the tractor, plus I have to start the tractor off the seat and it would be nice to be able to do it sitting.
I would like to use her plowing during the winter but maybe she's a southern girl and doesnt like cold.
Thank you in advance for any help
Sun Nov 18, 2012 8:19 am
I could be way off on this but here goes.
Have you adjusted the valves lately ? How old are the spark plugs ?
Are the points set correctly ? Is the carb idle mixture screw set correctly ?
My cub starts at 1/4 to 1/2 throttle, no choke, above 20 deg (F) 99.9% of the time.
Below 20 deg (F) I have to use the choke with the same throttle setting.
I know every tractor has its own personallity, but yours should not be that difficult.
Sun Nov 18, 2012 8:26 am
thank you for the reply. plugs are new, mag is rebuilt and I believe adjusted correctly, But valves have not been adjusted, the idle screw is adjusted but Im not sure if its proper.
Valve adjustment is that thing that sits in the back of my head that always pops up and yells at me JUST DO IT FOOL. would a valve adjust make a cold weather problem?
Sun Nov 18, 2012 8:40 am
Idle mixture screw could vary from the books setting, but should be within a half of a turn either way on most carbs I have worked on. I was the same way on valve adjustment. I could not remember the last time I done it. I finally remembered to do it earlier this year and it seemed to make a big difference in starting and running.
Sun Nov 18, 2012 10:16 am
Overall engine and component system health play a major role in cold weather starting success.
In colder weather, you have more things going against you. So the greater amount of things you can get going for you, will certainly speed slow starting complaints.
Valves in need of adjustment are just one of those little things combined with other little problems that will add up to prevent quick starts when cold weather sets in, perhaps not so much noticed in warmer summer temperatures.
If I understand your cold weather starting procedure correctly, success is achieved by pulling towards the front of the tractor on the governor control rod. By doing this you are closing the throttle against governor spring pressure, which you could do from the seat with the speed control lever by pulling it back. Pulling or pushing on the governor rod as long as its not done with force won't hurt a thing.
When the engine is stopped, advancing the speed control forward to the starting position opens the throttle plate. Apparently, your throttle plate needs to be closer to closed for starting, which could be a sign the carburator needs adjustment or serviced.
If your tractor will start in a reasonable amount of time in cold weather (after a few seconds of cranking), with the speed control lever forward just a little or left in the idle position while working the choke, you may have nothing or very little wrong with your tractor. Maybe a little fine tuning here and there will get it to light faster.
As others have mentioned, no two tractors are alike. It may be a matter of simply finding the sweet spot when setting the speed control and working the choke when the weather turns cold.
Sun Nov 18, 2012 10:47 am
First, I would clean and then lubricate with a good penetrating oil all of the joints/connections/sleeves in the governor circuit as shown below. That would allow the governor rods etc., to operate freely.
Then adjust the valves according to the valve lash procedure:
Recheck your tune up. You shouldn't have any difficulty starting your Cub in cold weather.
Sun Nov 18, 2012 10:00 pm
How long since mag was rebuilt? I have had this problem both from bad spark plugs, and a mag coil starting to weaken.
Sun Nov 18, 2012 11:49 pm
low compression and a weak spark play a key role in cold weather starting.
Mon Nov 19, 2012 4:23 am
Is the starter in good condition? This fall my cub became harder and harder to start, and needed more and more choke to start. I blamed it on the colder weather. Then one day the starter died. After the starter was rebuilt the tractor starts right off with nearly no choke even though the weather is now colder yet.
Mon Nov 19, 2012 7:13 am
I rebuilt the mag in apr thats when I gave her the name Maggie
since thats what got her going. the starter is good and strong Im thinking maybe its time for the valve adjustment. Can you adjust valves with the exhaust manifolds still in place?
Mon Nov 19, 2012 8:38 am
Farmall X wrote:.... Can you adjust valves with the exhaust manifolds still in place?
Yes. You will need to disconnect and remove he throttle and choke rods from the carb. The carb does not need to be removed.
Mon Nov 19, 2012 11:14 am
Ray thank you and everyone else as well. guess I know what Im doing tonight.
Mon Nov 19, 2012 11:28 am
Conduct compression tests on cold engine.
Your hard starting problem in cold weather could be the result of several problems. First one I thought of was that the linkage to governor is not properly adjusted. Second thought was mentioned by Rudi, sticking governor parts. Third thought was the technique used to start engine.
Last thought, other than weak engine, is a low fuel level, float setting, in the carburetor.
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