Inconsistent fast idle

[Jerome74911S]

I've done my searches, but of course my details are different. . .

The engine and transmission were just put back into the car, having been taken out for a transmission rebuild. Aside from a valve adjustment and new spark plugs, not much was done to the engine.

On today's shakedown cruise the hot idle would not go below 1200 rpms. Sometimes when I stopped the idle would be a steady 1800 rpms, next time it would be 1500, then 1200 again. It did not flutter around, but just stayed steady at a too fast idle speed.

Maybe vacuum leaks - I'll check tomorrow - but what else? As I said, nothing was intentionally changed on the engine.

It's a '75 S engine.

[Bob Kontak]

It is more than likely a vacuum leak. Check distributor advance hose. I don't think you have a retard hose like on my 81. An injector could have been bumped out of an intake runner during all the work. Oil breather hoses on tight at the tank and connections? Brake booster hose clamped down tight (if installed on a 75?). All the cadmium plated flying saucer and AAV / AAR CIS connections tight?

Did you replace any gaskets / boots on the intake runners - that's where I had my problem recently after a trans rebuild (and some gasket and cam oiler line replacements)

Double check your timing.