tii Injection pump / throttle synchronization

[schuetz1619]

The 02 factory service manual is confusing in its instruction re "Synchronizing throttle valve with injection pump" (13 54 004)

 

(1) Back off the idle screw, loosen clamp on throttle cam shaft

(2) Insert the 5 mm. hook through slot 1, into the back of the pump to hold the cone still in idle position

(3) Insert the 4 mm. pin into the tuna can hole, pull cam against pin, tighten clamp.

 

If you do this, you should be able to remove the pin and reinsert it, with the cam remaining in the same, tangent position, right?

 

But then, in the very next picture (top of page 13/54/2), it says that that when you remove the hook, the cam should partially cover the hole. (There is no reference in the Kugelfischer manual to this.)

 

If the calibration hook goes through the proper slot and into the hole on the back of the pump in the absolute minimum, idle position of the cone, how can the cam rotate to partially cover the adjustment hole when the hook is removed?  

 

This would imply that there supposed to be some lash, to the lean side of idle position, in the travel of the pump lever. I don't any have such lash. On my car (newly rebuilt pump from Wes Ingram), when I remove the hook, the cam in the throttle body stays exactly where I set it: tangent to the hole.

 

What's the story with the mystery movement of the cam?

 

 

 

[jgerock]

Not sure but I am wondering if they were trying to accommodate for some play in the linkage. As I have said before- only use the factory settings as a baseline.  Start there and tune to your tii's needs.  Trying to make your tii run using the KF instructions may not work for your car- it didn't with mine.

[wegweiser]

I know this procedure well. The pin gets you in the ballpark….close….but not perfect. On my own tii (72, plastic runners, early pump, 10:1 Mahles, correctly curved distributor) I find that I need to cover a substantial portion of the hole (maybe even a micron more than the photo above shows) in order to get a rich enough mixture at lower rpms, and to avoid the "popping exhaust" on engine braking deceleration. I have little / no data to back this up, but I think modern fuel requires a slightly richer mixture to keep a tii happy. Others with AFM set-ups (and hours and hours of tuning / testing with them) can verify the results of their experiences. 

 

YMMV. There's a ton of info here on tii fuel mixture experiments and tuning. My thinking is: If it gets more than 22mpg at 85mph cruising speeds (with a 3.64 diff and a stock 4 speed *weeeeeeeee!* ….and if it doesn't make me choke or foul plugs at traffic lights (or surge up and down from a lean idle condition), I'm damn close and pretty happy. Eventually I'll get an AFM set-up and then I will drive myself mad, seeking perfection. I'm not sure I'd be happier - but at least KNOWING the mixture would offer peace of mind that I;m not melting anything on high speed / long distance cruises.