Hi All-- does anyone's motor run up in the 1100's or so once it's been driving a while? I dont drop back to the 8's when I come to a light... I had Cliff Ruggles the Rochester QJ guru rebuild it and it works great right out of the box, but this little anomaly is vexing,..

Check that your choke is coming off?

Before I leave it does come off and throttles down to about 850-900... but why would the choke come back on while driving?

I would not expect it to in that case, but it wasn't clear the details of the problem. You could still confirm though, to at least rule that part out. Usually high rpm is related to air (either choke or vacuum leak). One other possibility could be the centrifugal timing advance sticking.

Have you tried blipping the throttle at a stop? When you shut the vehicle off, does it restart and idle down?

Unfortunately I'm not versed in Qjets to know how they specifically could contribute.

Yes, tried to pop the gas at the light to get it to check. I'm starting to think that its the mixture at idle setup? Maybe I'm set too high so that it runs when cold, but once hot is to open?
Still hoping I hear back from Cliff Ruggles. He's got his fingers in QJ's, not keyboards, so need to be patient!!

Head scratcher...

First, the idle seems a bit high to begin with.
Have you tried adjusting the idle speed when the engine is warmed up?
Next, the hot idle compensater may be opening up when it gets hot. It's basically a controlled vacuum leak to increase the idle speed slightly when the engine gets hot. It uses a bi-metallic strip.

Cliff says they aren't needed and the port can be plugged off with some lead.

Your hot idle sitting in neutral should be between 600 and 700 RPM's.

If you haven't purchased his book, I highly recommend it.

It could be many things but a quick and easy one to check is to make sure the throttle stop adjusting screw is resting on the lowest part of the step cam when at idle with the choke fully off if you are not using the stock Idle stop solenoid. I have seen this problem with some poorly made aftermarket throttle cables or poorly matched carbs and ends up holding the throttle slightly open. Engines tend to run a little slower when not fully warmed up but off the choke which would help explain why it gains a little when warm. Same goes for a vacuum leak.

Good thoughts--- I'll take a look at the adjustments
Thx guys

Edit: Is this the screw I should tweak?

I did not realize you hadn't made your basic adjustments. Here is a video to help you understand which screw does what https://www.youtube.com/watch?v=yX_hCujFQ_I and one from Harold's HO page to help you understand. https://www.firebird400ho.com/carburetor-adjustments/ The other thing I was talking about- the cable being to short and not allowing you to get base idle is something to check besides a vacuum leak if you can't get your base idle. remember to only make the base ide adjustment after the engine is up to full operating temp. As far as fast and curb idle speeds use what Pontiac specified most people with stockish motors are happy with that. Here is the service manual to help out https://www.firebird400ho.com/mdocuments-library/ if after getting all your base adjustments correct and making sure your throttle cable is not holding it open you still have your rpm problem it will be easier to narrow it down.

No worries--That is an old picture -- just used it to ask the question. Since then, I had it rebuilt by Cliff Ruggles and it runs great. The issue is just the high idle. I read recently that base idle timing if too high can result in a faster idle when warmed up, so I think ill check on the base timing (I'm set at 10BTDC, which is a degree higher than spec on the 400) and advance a few more degrees at base and see how that does....