I finally was able to get my buddy over to help adjust it. He did the exact thing I was told here. He moved the mixture screws and backed them out 2 turns. It ran for awhile and we got the idle about right 800-850. That curb idle screw was shorter than the one from another TQ. So I actually swapped it with one from a Holley 1920 1BBL which was the same length as the other TQ. I wasn't able to keep the screw from the other TQ because the guy didn't want to break up a good carb for that. Then after awhile it started to automatically idle up to 900-1000 and then the fan clutch came on. I checked the gauge and it was getting pretty hot so we shut it off. It may have been low on coolant. The expansion tank was empty and when we shut it off and I released the radiator cap valve it all went back in the tank. It didn't overfill or anything like that. Everything's new on this motor. Water pump, temp gauge, ported vacuum switch, thermostat, hoses, radiator, water valve, heater core. So it may not have all been full. Or do I need to run it with the cap off to bleed out the air? I guess it will get hot just idling but I guess that ported vacuum switch was working maybe that's why it idled up. Plus a valve cover kept dripping ever few mins right on the manifold and it was annoying. Do I need to put a fan in front of the radiator while adjusting the carb idling? What about that Water Wetter stuff from Redline, is that worth putting in? I sure don't want to melt the motor just adjusting the carb. It got pretty close to the H on the gauge. I can see this might be a problem on this motor. The thing sucks up coolant, the radiator is a little bigger than factory, like 27x1 1/2 core. I do have an original 28" shroud, new HD fan clutch, and 7 blade 20" fan.

I'm glad you got the idle to 800-850rpms.

But why did the engine temp almost get to H so fast just by adjusting carb idle ?

Did you fill your radiator with enough water ?! The level should be about 1" shy of the filler neck. Yes, Water Wetter is a good thing to add, can't hurt. Just don't add too much anti-freeze as Water Wetter works best with straight water however, you do need some anti-freeze for anti-corrosion protection. Less than 50/50 mixture is okay.
No, you don't have to leave the radiator cap off to vent.
Best to leave it on because as radiator/coolant gets hotter, the pressure cap actually helps suppress overheating.

What t stat are you running? I run 180 in mine and no problems. It might help if you raise the front of the car and burp the system. Raising the front will help in getting the cooling system free of air. Once you have done that fill the rad and run it for a few minutes to get it up to temp. Let it cool a bit and recheck your levels. I drilled 4 - 1/4 holes in my t stat around the spring to allow the coolant to move some before the t stat opens. You might want to check the stat in a pan of water, place it in there and let it heat up, if you have a thermometer that you can track the heat level and see if it is opening at the proper temp. It is possible that you got a bad stat, seen it before.

I'm running a 180 thermostat. I'm running a 16LBS cap I think is what it said on the top. I don't know if it makes a difference but the temperature outside was in the 90's and high humidity here in GA. It was in the garage with all doors and windows in garage open. The hood is still off too. I don't know why it got up that hot so quick. It pulled all of the coolant from the reserve system but when we shut it off and lifted the radiator cap release valve it put all that coolant back in to the reserve tank. So I don't know if it was low or not. It's been sitting for 5-6 hours now off and I went and looked under the cap and I can see coolant. My luck it's probably a stopped water passage or something major. We had it idling for 10-15 mins. I know several mechanics have told me the added friction of a newly rebuilt engine will cause it to get hot a lot quicker until it's broken in. This motor definitely gets hot quick just the feel of it. So I don't know if it will settle down if it gets out on the road with some air coming through. It hasn't been on the road since I've gotten the motor back in which was several months ago. I've been doing all the labor and trying to figure out the problems by myself and with help here so it takes me a lot longer to figure it all out. I will get some more coolant and some Water Wetter tomorrow. I only had less than what it called for on the bottle because I used it on another car. Amazingly there are no leaks from underneath and no coolant smell.

I checked my papers I am running a 180 thermostat but I believe it may have been a new one that had been sitting in the water pump housing for awhile. I talked to some of the veteran mechanics in the area where I work and a couple told me I could drop in maybe a 160 degree thermostat and it should help. They also said you're original gauge could be off. All I know is the fan clutch started working and it idled up automatically meaning the bypass valve was working and it comes on at 225 according to the Chrysler manual. Is it ok to change the thermostat to a 160, top it off with 50/50 and add a bottle of water wetter? Hopefully that will cool things down.

Have you checked the t stat like I suggested to see if it is in fact opening? And at what temp? It could be faulty. I guess you could run 160 but 180 should be sufficient. If you switch the stat out I would just top it off with the wetter and straight water. You don't want to run too much coolant with the wetter as it doesn't work as efficiently. Check that t stat first before you drop to 160 and see if it works.

Here is the thermostat I just pulled out. What a pain to get to the thermostat housing bolt next to the A/C compressor sump. I have no idea how I'll tighten it back up without removing the compressor. I took out this thermostat after it was running hot last week while we were adjusting the idle and mixture. This is what it looked like. I ordered a new one, a Failsafe but I ordered a 160 degree. I see this one is a 180 degree. Is it stuck open or closed? Should I reorder a 180 or is it going to cause any problems putting the 160 degree thermostat in. I know in the 1973 Charger owner's manual it says it doesn't recommend a 160 degree thermostat but I don't know the reasoning behind it. All the shops I've talked to said it should be fine. I can order a 180 degree thermostat it's just going to take a few days for the failsafe one. What likely happened to this thermostat? It's brand new. Any suggestion on what tools I need to successfully tighten the bolt closest to the A/C compressor sump without having to remove it?

Looks like it's stuck open. It is my opinion that you run a 180, stock t stat for mopar engines is 195. A 160 stat in hot climate could be a little rough on the engine IMO. A 160 stat would be OK in a race application or no stat at all. If you run a stat that doesn't allow the engine to warm up to a happy temp it could sludge up your engine. Running a cooler engine will increase power but with a compromise. If you run the 160 I would change your oil more often due to the possibility of sludge buildup. The engine will in effect burn off some of the sludgy crap if it runs a little warmer, at least that is how it was explained to me. Also a warmer engine will expand more than a cooler engine and help reduce wear.

Edit: Do you have a distributor wrench? You might try that, it might get you down and under the obstacle, just a thought.

I guess I'll go to Summit Sunday and pick up a good quality 180 thermostat. Are the Milodon or Mopar Performance thermostats ok? They call them all high-flow thermostats on the Summit website. They also have Mr. Gasket. I went with the Failsafe from Autozone just in case it gets stuck when I'm driving, which it did but wasn't driving it still didn't help though. If I would've been driving I would've had to have pulled over and shut it down anyway.

I just run an over the counter from NAPA, and have had no problems. I'm sure the others would be fine too. Make sure you grab a gasket.