Old JD

G

Garo

Well-Known Member
Member
I own a fully restored 1948 JD B and a 1953 JD 40. My son recently asked me a question that I haven’t the faintest idea of how to answer. Why does the 40 idle so slow, getting the full “putt putt affect” whereas the B runs at a much faster pace? Carburation? Camshaft?
Any insight is appreciated.
 
You should be able to adjust your idle with the idle top screw. You might have to reset your mixture adjustment after doing that. The 2 cylinder JD's that I've owned and been around have all been able to idle at low RPM's unless there is a problem elsewhere in the engine.
 
A belated thank you for your response. Now to the 40 After bringing it back to life I now have an issue I did not have before when we first got it running. There now is a delayed response when I move the throttle lever from slow to fast or fast to slow. It runs well at either speed, it just takes a few seconds to get there. It almost feels like something is bound up. Of course I have all the sheet metal back on. Could it be a cable or maybe carburetor adjustment? Stumped
Thank you.
 
Would suggest checking the linkage components to make sure they are all moving freely without excessive slop at any of the joints. Looking at the parts diagram make sure pin #1 is not broken as it appears to move shaft #7 which then connects via #15 to the governor and the governor connects to #25 to control the throttle plate position in the carburetor.
JD40 Throttle Linkage.jpg
It could also be something in the actual governor area since it is what actually moves the throttle plate as engine load and throttle lever dictate what the constant engine speed is that is desired.
JD40 Governor .jpg
 
Thank you for your great input. Your info along with the general feel of the throttle lever lead me to believe something was bound up. So I just removed the hood, started it and everything is moving freely! It accelerates and decelerates fine. I now have to find what exactly was hindering the movement. Seems odd.
Thank you so much!
 
Here is a view of the other side. I tend to agree with you but I swear the old one, which was a real booger to get out, was turned as shown here in the second photo. As many crazy things that I found on this tractor, nothing would really surprise me
 

Attachments

  • IMG_7040.jpeg
    IMG_7040.jpeg
    334.3 KB · Views: 7
Parts listing shows item 1 as flat side out and spring towards lubricant in the diagram. Unless otherwise specified by an installation manual the spring side should always be towards the lubricant to protect the spring from physical damage (and keep the spring from rusting) so it can continue to do its job during the life of the seal. Looking at the 3rd illustration it could be argued that the spring side is facing outward which might be why someone installed it backwards or they may have been trying to locate the rubber part of the seal lip so it ran on a new surface on the shaft to try and stop seepage?? If the shaft is marked up (or scored) you may be able to purchase a speedi-sleeve to install on the shaft or perhaps use a product such as JB Weld to fill in the grooves and then file the surface smooth once the product has cured.
1758313649211.png
 
You must log in or register to reply here.
Back
Top