Idle Puzzler

[patzim]

'77 K Jetronic CIS

Replaced points with pertronix electronic ignition. Before Pertronix, car had cold-start wandering idle but was fine when warm and had a consistent idle of 950 rpms after warmup.

With addition of Pertronix, cold start wandering problem is fixed but new issue is "high idle". After pertronix install, the higher idle was immediate. I warmed the car, backed it down to 950 rpm's w/ idle screw, set timing to +5, and thought I was done. Not so.

Now, on cold start, idle is at 950. After stepping on the gas or driving it, it goes to 1600. Here's the strange part - if I partially release the clutch (while in gear) causing rpm's to drop, the idle will then return to 950 and stay, until I step on the gas again. Then it's right back to 1600.

How do I diagnose this? Thanks, Pat

[Porsche Doc]

Did you reset the timming?
If not! Reset set it, and that will take care of it.

[TurboBert]

If I had to guess, it sounds like your centrifugal advance is sticking in your distributor. This would cause the weights to not pull back at lower speed, causing a higher idle. When you use the clutch to force a lower speed, they reset.

[patzim]

Your responses prompted additional search. Thanks! Found this link that I'll probably print and frame. If you have distributor questions, or just need hard to find info and schematics, this one is incredibly helpful: distributor lube...