Case Sc trouble

I have a 1949 Case Sc that used to run amazing I raked hay with it last year and 2nd cut I noticed I very slight change in the sound of the engine but it was really slight. So I kept raking after a few days it got so bad that it would barely run. So I replaced the intake manifold gaskets because they looked worn out and It didn?t change anything. I totally rebuilt the carburetor and it helped a little but not a whole lot. It runs okay at lower and mid throttle but when you give it higher rpm it?s surges. It runs high then idles way down then revs back up and it won?t stop. Is it the valves in the engine or a govener problem? Thanks for anything you might think.
 
They are known to blow holes between the intake and exhaust inside the manifold. Wonder if there was a small rust hole and gradually got bigger. Other thoughts go to condenser or electrical issues not getting full spark all of the time. Did you check all the electrical connections? Just have to systematically go through issues.
 
Fuel supply? Disconnect the fuel line at the carb, or better yet pull the carb drain plug, make sure you get a good steady stream. Catch a quarter-cup or so in a clear jar or bottle and make sure it's not contaminated, tractors don't run well on water. Adjusting valves is a good idea if it's not been done recently. Look at your spark plugs, any fouling? What type? What color is the ceramic (inside the cylinder, not out)? Run a compression check and look for a good hot spark at each plug. Does the exhaust sound good and loud, or is it too quiet with a hissing sound? That indicates a clogged exhaust. A physical examination of points, cap, rotor, wires, distributor shaft wobble etc. is in order. And the month after that...
 
Have you drained the carb. and made sure you have a good flow after the bowl has drained? Might try a can of injector cleaner in about gallon of gas, might clean it up if it is not really nasty.
 
It has nothing to do with the valves. Weak spark won't cause it to rev up and down. You have a governor problem or carb is too lean. I would put my money on the carb or fuel issue.
 
(quoted from post at 05:50:45 04/08/18) Yeah that is what I am going to try, the exhaust sounds deep and it
kind of backfires through the air cleaner

How well did you clean the carburetor? The surging governor and backfiring through the carburetor means the carburetor is too lean. You might have some passages in the carburetor plugged up yet.
 
Sounds like a problem with the governor unit, if the carb is functioning properly and the gas is clean and fresh.
Jim
 
Exact same symptoms as my '48 a couple of years ago. Only really used for raking too. Chased ignition for ever, since "carburetor" is a French word meaning LEAVE IT ALONE. I was sure it was weak spark, under load. It turned out to be an internal corroded hole between the intake and exhaust manifold. I Swapped an old dual fuel manifold on, and problem was gone. These systems are simple, fuel usually won't change unless someone starts twisting on things..............
 
After reading your post again, I?d definitely look at the governor unit for wear. There is a thrust bearing that rides on the governor arm that can go bad. Remove the oil filler cap and look for metal shavings, etc. I had to replace that unit on my SC once.
Jim
 
Also, SC valve springs are known to weaken with age. Could be you need a new set of valve springs or "adjustment" to the existing springs. We corrected a similar problem several years ago after chasing all of the above mentioned problems. We put a flat washer under each valve spring between the head & spring. Just make sure the center hole of the washer allows it to fit flat against the head. The old girl has been running fine for years with this fix. Held the valves up with air pressure using an old spark plug with soldered in fitting to connect to air compressor & changed the springs with head on the block. (My $0.02 worth. jal-SD)
 
(quoted from post at 07:47:10 04/09/18) fitting to connect to air compressor & changed the springs with head on the block. (My $0.02 worth. jal-SD)
I was using this trick once when someone came by and needed my air hose worse than I did. At least he thought he did. Since then I've filled the cylinder with rope, leaving a tag end of course, and brought the piston up as far as possible. Much less prone to accident.
 

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