I have been doing a bit of research. Is this pump called port helix metered pump?

 

Yes this is the type pump the Kubota engine use. I found this site that gives a good description of how it works.

Pumping principle

 

Thanks for the link. Here is one that helped me quite a bit with the theory.
" transportation.centennialcollege.ca/.../inline.pdf " Not sure if the link will work as it is a pdf.
So you moved the barrels. I guess to raise them? or twist them away from idle? to increase stroke before the spill port opens?
My question is did you notice any negative effects at idle or engine shutdown?
I have never done any pump work or mods. I need to wait until I get a spare pump. I am cuious if all the internals are as interconnected as reported? More fuel at the top end= less fuel at the bottom end?
I would have originally thought you would have re-indexed the junction where the rack and the plunger meet, to give ( i don't know ) more or less twist?
This is very interesting. How did you figure it out to move the barrels. Is this posted somewhere on a different thread?

 

Yes, by moving the barrels it adds more fuel before the plunger reaches the spill port. No negative effects only positive! HUGE difference in the truck from idle to wide open. The increase was across the board even, it changed the way the engine sounds at idle and how much torque it produces at low RPM's. As far as the rack goes, there are indexing marks on rack inside the pump that coincide with the sleeves that rotate the plungers. I did experiment setting the rack off one tooth but wasn't comfortable with it, not saying this wouldn't work, it's just not how I did it. I finally figured out, by studying the pumps and carrying around a plunger & barrel in my pocket, how to do it. You'll do well to find a second pump and tear into it, you can't really mess it up unless you really try. Hope this helps.

 

Now this is getting interesting. Any idea how these mods will affect longevity? I really want one of these motors but I'm so scared that tuning it for the power.I want will kill the reliability

 

I have also been conversing about this in a a mercedes diesel forum. the consensus for the inline bosch pumps on the OM617 benz is that clocking/turning the barrels will give a good amount more fuel, but getting the clocking correct so that all cylinders receive the same amount more fuel, is extremely difficult to do with out a pump test bench.
The procedure on the bosch pump seems very simple to do, but very difficult to get correct. I still want to see what is involved to do the mod on the Kubota.

Usedkubotaman, do you have any more details or pictures about what was involved for you?

 

Just picked up a non-turbo DI, have been reading-up on all this stuff, and wanted to say thanks for sharing all this info with us. Very helpful.

 

Welcome to the team jesusgatos. I am working on getting all my pictures of my double v-belt set up i finished last night and I am working with the machine shop that did work for aaron looking for people who need an adapter to bring the cost down. PM me if you need any help

 

Thanks. I'm planning on using a 4spd muncie behind mine, and Greg at Overland Diesels is working on a Chevy adapter, but not sure what I'll end up doing. Just finished reading all the build threads I could find and learned a lot from what other people have done. For a low-budget adapter, think it'd be hard to beat milling the Kubota flywheel housing down and then making a steel adapter plate like Kubotaman has done. Super-simple. But I'm a product designer and do a lot of CAD work, so it's tempting to have a nice billet adapter made that would bolt right to the back of the block.

 

I know exactly how you feel! :sly:



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