Redhotnrolli_n
Guest
If the injection pump is the distributor type as found on other 400 series engines, you will typically find two adjustments. One is for low idle speed, the other for high idle. These adjustment screws are external, with no disassembly of the pump required. These screws are "bump stops" to limit travel inside the pump housing. Seems the screw with the "acorn" nut is high idle as I recall. There are shaft speeds published in one of the tech books IH put out telling what speed the beater or other component should be at high idle. I used that method once when a faulty tach was suspected, to find out where I was on engine RPM then set engine speed accordingly. The mechanic used a hand held snap-on meter that read off a piece of special tape applied to a shaft on the separator that was to turn 816 RPM when at high idle and that's the way we set the engine speed. Maybe your setup is different, but that's what I did.