1948 JD B throttle linkage

[Markpa13]

I got a 48 John deere B that seems to be having some sort of fuel issue. When I first put the tractor together, I did not have the throttle linkage, so I made my own
piece to go from the governor to the carb. The tractor would run good, but the throttle would surge with the governor. So I picked up the proper linkage from ebay, now
when you give it gas, it wants to take off at crazy RPMs, I'm guessing 2 - 3K rpm. How the motor hasn't blown apart is beyond me. I've been researching online and
haven't found much as to what would cause this. I read somewhere about governor weights, but they seem to be intact and proper. The tractor is newly rebuilt and a re-
manufactured carb. If something was sticking in the carb and it was flooding the motor, would it cause this run away? Also, in case I don't have the linkage together
properly, can some one send me a picture of how the throttle and choke linkages are set up on your Model B? I can't seem to find any images of this either. Thank you!

 

[JD Wayne]

If you go to deere.com and look under parts, click on the link that says search parts and type BN in the search window. It will then give you the pdf file for all parts and breakdown of how they go together for your throttle. When the pdf uploads click on the + symbol next to the letter C and it will open all the subcategories, and there you will find controls, throttle which will show you if you have it together correctly.

 

[RLA]

With the throttle hand lever wide open, engine off, the rod from the govener spring to throttle butter fly should
be 1/2 hole short from falling into the linkage hole... Do this adjustment first..

 

[James Howell]

Take a look at the parts diagram below.

Note the throttle rod (Key 4), 1/4 nut (Key 5), throttle rod end (Key 6), and governor arm (Key 23).

Reviewed the [b:654c4848f0]SERVICE MANUAL ON THE JOHN DEERE B TRACTOR SM2004[/b:654c4848f0] under the [b:654c4848f0][i:654c4848f0]Control Linkage[/i:654c4848f0][/b:654c4848f0] topic and [i:654c4848f0]Throttle Control Rod Adjustment[/i:654c4848f0] paragraph on page 110-10-3.

"[b:654c4848f0][i:654c4848f0]If throttle control rod does not adequately regulate the engine speed it may be adjusted. Note that the rod is threaded at the end which is connected to the governor arm and secured with a jam nut. To adjust rod length, disconnect rod from governor lever arm and loosen jam nut. Move speed control lever to the wide open position. Set throttle disk in wide open position. Lengthen or shorten rod end until the rod is 1/2 hole short. Place into position and lock jam nut.[/i:654c4848f0][/b:654c4848f0]"

Take a look at the photo below of "Uncle Earl" our 39B.

Note the distance between the governor arm and speed change spring is approximately 1/8 inch.

Take a look at the photos below of the choke levers on "Uncle Earl" our 39B and "John B" our 43B.

Hope this helps.

 

[RandyB(MI)]

Good info down below. It's not a carb problem just to answer your question. With no load and throttle lever on steering pedestal wide open, the governor/linkage (if working properly) will hold the butterfly at just a tad past idle. A throtle plate might stick in closed position but never in open position. Not the carb.

 

[Rich Duane]

Also make sure that the cotter pin in the linkage at the carburetor is not binding. (The lower cotter pin)

 

[Pete in MD]

Have you by any chance had the cast governor arm, #23 in James' parts drawing, off the governor's vertical shaft or changed the big flat spring?

If so, check to make sure the end of the set screw, #19, is lined up with and goes into the small hole in the governor vertical shaft. This puts the governor arm in time with the two control rods and keeps the vertical shaft from turning inside the governor arm when the governor tries to throttle the carb from running away.