75 1.8 vacume advance/retard

dave blackburn · 05-20-2002, 09:29 PM

Hi, I just bought my first 914 1 week ago (75 1.8L). Car did not run, took me about 2 days but i got it running ok. Replaced ignition, runs better, replaced all vacume lines, runs even better, checked and cleaned all FI components runs great. The two things i am having a problem with is the idle is to high 1100 rpm, and i cannot find out where to hook up the distributor vacume retard line. If i rev the engine high, on retuning to idle it sort of backfires or something. I checked out the vacume advance line hooked up to the throttle body with a vacume guage and it has good vacume on idle, but when i rev the engine the vacume drops to zero and stays there. Is this right for advance? I have checked out the diagrams ect. and they say i should have two lines comming off of the throttle body to the distributor (one for advance/one for retard) but i only have a place to hook up one. All the other lines are there and hooked up right, no vacume leaks and it still idles high. I did the timing and tried all the adjustments and get nothing. Thanks for your help, it is realy hard to find anything about 1.8L out there. Dave

Jim Chambers · 05-21-2002, 06:13 AM

My non-California (no cat or EGR system) '75 1.8 only has one line to distributor. It connects to the retard side of the diaphragm (toward front of car). The advance diaphragm is left open, though it often has a short hose attached which goes nowhere, hiding under the intake manifold to fool smog inspectors. If you have only one vacuum port, connect to the retard only. There is no vacuum advance.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Quite correct.

Seeing vacuum at idle and not at any other time also tells me that the poort you were testing is for the retard. That will help pull the timing back some at idle and get the idle RPMs down to where they should be.

A vacuum advance fitting would have nothing at idle, and just off idle (with the throttle plate just barely opened) it would show vacuum. The vacuum would go away as the throttle opened up further.

--DD