building hotrod 12mm ve pump and having a problem with "K" setting

[vwjunkie53]

Hey folks,
I'm building a 12mm pump for my D24T.  I've done quite a bit of reading, including the mtdi pump thread, and had come across the KF and K measurements on that thread.  According to what I read, I should be shooting for 3.6-3.8mm for the "K", however my pump only has about 1.5mm.  This is a new aftermarket 12mm head and rotor.  Just to make sure I didn't assemble something incorrectly in the new pump, I installed the head and rotor in another complete stock pump I had laying around.  I first checked its K measurement and found it to be about 3.7mm.  After swapping on my 12mm assembly I came up with almost the same reading as the other pump...  The shim on the cam plate isn't super thick, and between the two pumps they were within .005".  I could remove the shim and still not come close to the K setting I need.  Is there some spacer somewhere else I should look at or someplace I need to remove material from to get the K setting up to what is should be?

Thanks,
Jason

[rallydiesel]

Doesn't KF and K vary quite a bit between idi's and tdi's? How do you know it will translate to ~3.6mm for a 6 cylinder Bosch pump?

[vwjunkie53]

There wasn't a different measurement listed for the K setting between TDI and IDI, only difference I found was for KF depending on what springs you have.  Also, the 3.6 to 3.8mm measurement agrees with what I found on my other stock 6cyl D24T pump.  I was assuming I would want to shoot for that same range with the new head and rotor.  Right now, the rotor at full lift actually protrudes past the bore in the head slightly. It doesn't hit the thread in cap, but its gotta be very close.  In the thread it was warning against less than the specified measurement running the risk of the rotor shaft smacking into that cap at high rpms.  With less than half that measurement I'm thinking thats not gonna be cool.

Jason

[rallydiesel]

Yeah that would not be good. What brand is the head/plunger?

[vwjunkie53]

Its a Chinese one, I bought it directly from the manufacturer.  I know its not Bosch... However, I talked to a number of D24 guys in Europe that have bought and run this companies pump parts and had great luck with them, including the 12mm head and rotor...  I just talked to my local pump shop and they suggested I may need to run the cam disk that goes with the head, however it would be a DI plate for a cummins, and I had read running the DI plate on the IDI engine was less than ideal becuase of the different injection duration built into the disk.

Jason

[burn_your_money]

Bosch makes a spacer to go between the head and the body. I don't know what application it is from though.