Weber and Hot weather

I've noticed a new old issue lately as it has warmed up, the idle rises while I am driving. I notice it at stops and it won't drop unless I hit the gas and let off it quick. I have a feeling it will get worse when it starts staying over 80.
I had this problem only it was much worse with the old Weber when I first bought the truck and the 1/2" plastic spacer seemed to be the cure. I'm half tempted to pull the intake and drill out the coolant hole like Geezer described in one of his posts. I am using a regulator and the mechanical pump.

Any ideas? :shrug:

Ooooh this could be for a number of reasons. Is the pressure regulator freaking out from the increase in temperature? Check to see if your throttle stop and return spring is going out of adjustment. I should be up to speed on your install - but are you using the stock air cleaner or an open element? Don't know if it would cause this issue, but the Weber pulling hot air from the engine bay isn't optimal. It's not dieselling/running on or detonating so that is promising. When you get those symptoms you'll need to look at fuel pressure and coolant/manifold/intake temps. Other than that...:shrug:

Shut if off when the idle is high and try to slide a piece of paper or thin feeler gauge in between the idle speed screw and the throttle stop to make sure it is closing all the way. I had a similar problem that ended up being the throttle bell crank was binding with the choke arm. If I eased off the throttle it would bind. If i snapped the throttle and let it shut quickly it would have enough momentum to work past the bind and fully close

I used to have the stock Weber air intake now I have the OE air intake fit to it. I used to hook a spring to the throttle linkage to pull it closed when I let off. I might hook that back up to it. The pressure regulator is on the firewall right in front of the driver. I got it not long before I put in the new Weber. I'm going to put the point shoot temp gauge in the truck so the next time it happens I can get some readings.

I had to hook a spring to the throttle linkage on my weber. Failed emissions once because my idle was too high, the spring fixed that problem right away.

I took a drive today, it ran nice since the Restore sat for a few days, I got cement and some 2x4's. It was revving on the way home, nut not as bad as the other day when it was near 90. Opened hood with it running and the thermostat housing on the driver side was 182F If I stood in front and took it from the top it was 153F ditto on the hose. I did not think to take the temp of the pressure regulator. I grabbed the linkage and turned it closed it moved a tiny bit but the motor calmed down. I hooked the spring back up. I'll update if something new happens.
If anyone has ideas about why heat might do this I suggest we start listing them here.
Thanks for the reply's.

Brass spindle in an aluminium body and the two metals expand at different rates?

They do expand at different rates. This was probably a little over adjusted in the first place for it to go out of tolerance enough to impact the idle. The return spring probably also went out of tolerance too.

It is out of box adjusted the way they built it. I figured since I did something bad to the other Weber when I tried to "fix" it with a rebuild and adjustment following instructions I should just trust the pro's who built it to have done what was right. Experience so far says I am right in this. :)
I think the dissimilar metals may be part of it. I think my old motor maybe isn't cooling as well as it was designed to.