JD 4620 injection pump

Jacob B. · Aug 31, 2016

Hey guys I am pulling my 1971 JD 4620 this weekend at the local fair and I want to turn up the injection pump a little bit to get a little more horse for the pull but plan to turn it back down after the pull. The pump is a roosa master JDC625JT2398 pump and I just want to know how to get inside and turn it up a little bit. If anyone has any know how on this or any suggestions about pulling with a heavy hog like a 4620 feel free to chime in.

tim s · Sep 1, 2016

Not much that you can to in the way of turning it up,,unlike the inline pumps that can be grossly over fueled with a couple turns of a screw...

Dieseltech · Sep 1, 2016

If it has a torque screw back it out 3-4 turns, takes a 1/8 allen and 7/16 wrench. It's the angled screw in back of the pump housing if it has one, not all pumps used it. To correctly change the fuel setting that pump needs torn down since it's a four roller, not two. The roller centrality is VERY critical, and needs to be set on the centrality gage..

JD 4620 injection pump

Jacob B.

New User

tim s

Well-known Member

Dieseltech

Well-known Member

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