Cliff's Quadrajet Parts and Rebuild Kits

Hello - new forum member here. I am looking for a 7040268 for my 1970 GTO 455HO 4-speed. I just purchased the car and it has a numbers matching engine but the carb is an incorrect replacement unit. Hopefully someone out there has what I need!

thanks!

Aside from the goofy throttle arm and front inlet good choice for what you are doing.  Needs a little help in a few places.  I can supply a complete rebuild kit and tuning parts to set the carburetor up for the 454 truck application.  I would also convert it to electric choke, and make sure to check play at the primary throttle shaft it may need bushings installed during the rebuild....

  Thank you gentlemen,

 I appreciate your support. Novadude, thanks for the explanation about the acceptable range for the AFR during certain conditions. I had noticed that it would lean out as the throttle tipped in and then would richen up as the power piston raised.
 What is really worrying is when the AFR drops beyond what the gage can register at 18.0 and I can tell it's starting to misfire from being too lean at that point.
 I've been trying find the specific parameters where this occurs as it's not often, but I have seen it a few times.
 It's mainly when I'm accelerating slowly, but I've got to do it a few times to make sure I can duplicate it and explain exactly what the conditions are. 
 When I first posted this question I had not noticed this particular situation, I thought I only had an issue with the initial startup with the choke on.
 But at least I now know that a 17.0 with a light throttle is nothing to worry about. Thank you for that.

 Rick

There is absolutely no concern with being lean at part throttle / light load if it is not causing drivability issues.  Zero engine damage will occur. 

In fact, every text book about engines written in the "pre-emissions" era suggested a target A/F of 16-17:1 for best economy if the engine will tolerate it without misfire/ surging. 

Personally, I've dialed on my own Q-jet to go down the highway at 15.5-16:1 (level load, steady cruise).  The only time you need to worry about "too lean" is under heavy load.  Mine will trend even leaner (high-16s) as you lean into the throttle, until you get the point where the power piston spring overcomes vacuum and lifts the primary rods.  In my case, it took some experimenting with PP springs to get there.

Lean keeps the oil and spark plugs cleaner, and also has the benefit of keeping more gas money in your wallet.  LOL

^^^^ what 77 said.

QJ