IP pump vacuum?

[wade]

morning everyone!!! i want to try to time my pump on my 1980 300d non turbo,it seems to run fine but am getting alot of dieseling knock. i have adjusted the valves and it didnt help, so timing it is. my qustion is- the Haynes manual makes mention of disconnecting the vacuum line on the IP before using the drip method(lotsa luck). where is this line? my non turbo vac lines have almost all been removed....no door locks,and the climate control is manual controlled(european model).my vac lines consist of the trans line and the shut off lines to the key and back (and brake module). there is that little module looking thing on the side of the injector pump,it has a white little lid and there were vac lines on that at one time but are long gone,like i said the car runs well,no smoke and starts great,what is the purpose of vacuum on the ip? is this only for transmission shifting purposes? do i need this line to make the pump run correctly? the reason it was disconnected was that it was not holding vacuum and causing the rest of the system to leak. it is disconnected when you time the pump,so if it is leaking at that point, will it effect the drip method well timing? or is the drip way a bad way to time?