Idle worship

[stuartrubin]

I realize that the topic of fast idle has been covered many times on this forum, but I'm having a weird issue that may be beyond normal setup issues.

First, I definitely have some exhaust leaks at and around the manifold. Also, with my new carb installed at the end of last summer, I was never quite able to set it up properly. (I have new gaskets, etc., but just haven't been able to get to the muffler shop to have them fix it.) That said, until the other day, my idle speed was about 2000 RPM and things generally ran OK.

The other day while driving, my idle speed suddenly jumped to 3000. After a few minutes, it went back down. I assumed that the throttle or cable or something were binding. Driving the next day and today though it always starts at 3000. As the car warms up, it gradually goes to more like 3500. Took a good look at the throttle level, cable, etc. and they don't seem to be binding at all, and I cleaned and oiled them for good measure. No help.

So, what's going on here? I don't think it's the choke; I would expect the speed to lower as the car warmed up.

Is there a connection between exhaust leaks and increased idle speed?

Thanks!

[riverdadd]

i would disconnect the throttle linkage to rule it out.......maybe pedal is sticking and not allowing it to return?

I always set idle on all my machines with throttle disconnected, to get a true minimum setting

[stuartrubin]

Thanks, Riverdadd, I'm pretty sure (but not 100%) it's not the throttle linkage, pedal, cable, etc., but it very well may be something inside of the carb like the throttle "flap" itself or some nuanced feature of the 34ADF going sour.

Stuart

[riverdadd]

remove air cleaner.... remove throttle linkage.... open choke plate with a screwdriver... look down barrel of carb and verify the throttle plate closes fully.... maybe a set screw or something has vibrated loose and holds the throttle plate open further than it should, at rest... also verify a full range of operation, it sound like something is holding throttle plates open.....verify that no wires or anything is stopping throttle plate from closing fully.... hope that helps

[stuartrubin]

Looking around, I think the problem is likely related to this: http://www.fiatspider.com/f15/viewtopic.php?f=5&t=33638

Or at least I need to fix that before this problem!