John deere b Question

[Doggonetractors]

I have a 1948 John deere B and I do not have a manual for this tractor yet so my question is there is an adjustment screw ( just like on the hydraulis ) just below the clutch and to the right. What is this adjustment for? Thanks.

 

[Anonymous-0]

that is the engine oil psi aujment

 

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Just to add, the pressure should be set between 10 and 15 psi.