JDseller injection pump

JDseller, my fuel injection shop calls this a torque screw. My friend who owns shop has 35 plus years of experience in fuel injection. He told me if I back this screw out 2 turns I will have 10% fuel delivery increase.
I suggested to the man maybe his pump had this screw installed if his pump had been rebuilt.
WELL?

Thats interesting Mark. I've never seen a 4020 pump with that second adjusting screw, althogh I've seen it on many other brands and models. Having both adjustments lets you tailor both maximum HP and torque rise (lugging ability) What is the model number stamped on the tag? I'm thinking its actually a pump for a different model tractor or custom built.

The rebuilders around here eliminate that adjusting screw when they rebuild a pump. It is not uncommon to see them on Deere applications.

Your tractor didn't originally come with that screw. Other brands use it and all it does is make a more convenient location to increase the fuel delivery. The end of this screw is a stop for the metering valve inside the pump. What was commonly done was tightening the screw on the leaf spring inside the pump that controls fuel delivery which would allow the pump to produce maximum fuel. Then this external screw would be tightened so as not to allow the metering valve to open so much, thus making the engine produce whatever power level was wanted. I have one on one of my 4020's and don't really use it. The fuel is turned all the way up on it and this screw does not touch the metering valve. It's ran this way 32 years for me. Mike

I know my 4020 did not come with the screw originally. It was added at a rebuild.
This post is in reference to a post titled "4020" about four pages back where I was taken to the wood shed and told no such external adjustment existed.

That screw is NOT a easy place to adjust max fuel delivery if built to factory specs. Deere uses it on some Stanadyne pumps to limit engine torque rise at certain times. Thus the reason why it's called a "torque screw." The torque screw limits how far the metering valve can open -which basically works like the butterly valve in a carburetor except it restricts low pressure fuel flow instead of air flow. The torque screw does not limit max fuel setting permanently (except by a small amount). It only slows down the flow. So, when a load hits the engine fast, it takes longer for fuel delivery to increase with the torque screw. Max delivery will only slightly increase if the torque screw is backed out IF the pump is set up to Stanadyne specs (determined by pump ID plate #).

You can take two Stanadyne pumps used on the same model tractor. One with the torque screw and one without. Both have the same max fuel setting. If you back out the torque-screw on the pump that has it, max fuel delivery does not change very much. Max torque timing changes and so does visible smoke at certain loads.

I don't know why you have one on a 4020 but you didn't give the pump model #. Regardless, it has little to do with your max fuel setting IF built to Stanadyne specs. Max setting is done with the setting of the rollers and Stanadyne requires they be shimmed to limit turn up beyond .005". I'm sure there are people who put pumps together and not follow Stanadyne specs though.

Here's one example of a Deere tractor that came several pumps. Some with and some without torque screws.

2030 ag tractor:

JDB435AL2442 - with torque screw - at max fuel delivery pump flows 10-12 ccs per cylinder at max RPM. Rollers set at 1.9635" to 1.965"

JDB435MB2805 - with NO torque screw - at max fuel delivery pump flows 10-12 ccs per cylinder at max RPM. Rollers set at 1.962"

If you completely back out the torque screw in the first pump - you gain a max roller width of .0015" to .003" which isn't very much. Each increase of roller width of .001" gives a 5% increase in max delivery.

Maybe somebody customized your pump, removed the roller limit shims, turned fuel delivery way up and then tried to control it via an added torque screw? I guess this might cut down on visable smoke a bit under certain condtions if your tractor is turned up beyond factory specs.

My 4020 has that screw.Two years ago our big tractor had a problem the day we went to chop hay and the 4020 had to go on the harvester.I don't remember if we turned it in or out but it made a huge difference in horsepower and blck smoke as well.The screw got left where it is and now we hate to drive the other 4020. My son thought we added a turbo to the tractor.

The adjusting bolt you are pointing at on your pump just hits arm #2 that controls the metering valve #4 (both in first pic). If any pump repair shop is using this to set the total horse power on an injestion pump then they are doing a poor rigged up job. This is to set the torque response of the pump. It will not give you more total fuel delivery unless someone has set the injection pump wrong internally.

To correctly adjust the maximum fuel delivery you need to tighten bolt( second picture) #12. That spreads the retaining clamp #13 open. This lets the pistons #11 travel out into the cam ring further. This gets you a higher maximum fuel delivery.



The adjustment bolt you are pointing at does not change the maximum fuel delivery. It just changes when the pump will allow the maximum fuel delivery. You will not gain much horse power and you will make it smoke like a freight train.

I have set them on a dynometer where you can actually see the horse power not just guess because it is smoking more.