Sc still won't run right

ralf

Member
Tried adj. the carb from suggestions from pref. post still won't run right. I hit the starter and she fires right up but soon as I give it some gas it wants to die. Also wants to run rough however if I pull the plug wires off and just set them back on so the the spark has to jump to the plug it seem to smooth out. The wires are new, the plugs are Autolite 437 , could it be the plugs?
 
When you pull off a plug wire, it increases the reistance the secondary coil winding has to overcome, and if it's within it's capabilities it will jump with a hotter spark. I'd say you have ignition issues, and it could be any number of things. Breaker point systems are simple, using very basic inductive theory. All kinds of literature out there and advice. Check ea component carefully and you should turn up the problem. Electrical problems in the ignition system will mimic a fuel problem and lead you the wrong way. I used to teach Voc Ag Diesel, and with these types of questions I used to use the phrase that a "carburetor is a French term, meaning LEAVE ME ALONE......" Your basic updraft carb is as simple as any one cylinder Briggs and Stratton, only on the tractors it's bigger! Main circuit, idle circuit - That's it, no power valves vacuumed controlled enrichment etc etc, nothing like that. Search your ignition system. If you still have a mag, coils are weak and need to be given a "thrill" by a qualified mag builder. The permanent magnets weaken with age. The last years with the Alnico magnets are a much better bet if you insist on running one.
 
My 51 SO ran on all 4 cyl but did not run right after I rebuilt the engine last year. It coughed and sputered when giving it throttle had on a hard pull it would run out of pwer and ran rough. I messed and messed with the carb and switched carbs? Had spark to all four plugs. Last week we tweeked the carb a little to try to smooth it out. Finally we advanced the mag about 3/8" or more and now it runs like a singer sewing machine. I drove it about three miles this week to a tree planting project the tractor club helped on and it ran great even up a long steep hill pulling my trailer with my pick up on it.
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I would at least check to see if the timing was correct. I didn't want to mess in the flywheel housing on my 51 DC, so I put a pointer near the crankshaft pulley and marked the pulley at top dead center using a wire on top of number 1 piston to verify TDC and used a timing light so set it. I don't remember if there is a mechanical advance built into the distributor and don't know any thing about magnetos. But if there is a mechanical inertia advance, make sure it is free to move as it should.
 
The tractor is a 1950, it has a magneto (with eagle 0n it) didn't think it should be the plugs , used to take it on our tractor runs and it always ran like a charm just started this last fall when I was putting the old tractors up for the winter
 
This is a picture of the problem child. In reading how dacaseguy described the way his was running, mine seems to be doing the same sort of thing.
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Yes , wires are copper need to get her back over to the shop and try moving the mag. will see if there is any change
 
If it fires when you double jump the gap. (by pulling the wires off) That means the plug is fouled. Put in a new set of spark bolts and it will probably run just fine. (I won't say its that Chinese porcelain in them autolite plugs but sounds like that what the problem is)
 
(quoted from post at 19:12:29 02/07/16) If it fires when you double jump the gap. (by pulling the wires off) That means the plug is fouled. Put in a new set of spark bolts and it will probably run just fine. (I won't say its that Chinese porcelain in them autolite plugs but sounds like that what the problem is)

Klyde has it right, fouled plugs, I don't know about the Chinese porcelain tho in years past we went to Autolites to cure constant fouling. My motto is ABC, Anything But Champions.
 
ralf ,,, not sure if this was mentioned or not ,, The thin wall Intake exhaust manifolds could be burned thru and therefor sharing gasses where they mount to one another ,,, .ALL3 Sc's that misfired their way to my house from their disgusted owners was found to have this ailment , and it was ALWAYS hard to find the crack orburn out ,. they usually are repairable in the hands of a MASTER welder ,, the last one I had fixt cost me 250 bux , "a lot of nickel rod there , Boy! ... damthing kept falling in and showing more holes to fix,in thegotdamdesthard to get to places" he said ... sheesh ! ,, That durn Guy Should a told me to Buy another intake exhaust somewhere ,,. they are out there,,. I paid the welder master without a complaint , because I did not want to buck his personality . and make him sore to where he would set my Next broken stuff in the corner for monthes , until he was in the mood to ...fix sumthing I desperately need NOW .. a wise man chooses his battles ...
 
I didn't think of this either. My older SC pulled this,and I chased fuel/ignition issues all summer, changed manifolds, immediate solution
 
I have to disagree with the ABC comment. I have always run Champions in all my tractors. When I ran the Autolites they fouled quickly. Now, I run d21's in everything except my hotrod " M" when I am pulling or plowing I run d14's in her. But in the winter when she is not working hard 21's. I get all my plugs at Napa. Try adjusting the mag and see what happens. Please let us know what ya did. That's my 2 cents worth..............Kenny
 

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