I am in search of a 7040246 Rochester Quadrajet for my 70 GS 455. It currently has an Edelbrock carb and intake that I would like to make go away. Probably going to use a TA performance intake but I am having a hard time sourcing a carb. Any help would be much appreciated.
Unless your car is a '70 Stage 1 and you are trying to make it all matching numbers, I would highly recommend that you use a different part number and save yourself a lot of searching and a bundle of money. A 7040246 is going to be very expensive just because of the numbers stamped into the body.
Contact either the Sloan Museum in Flint, MI or Wayne Roberts at the GS Historic Society - depending on your build date. With your VIN, either one will tell you what the car originally was.
I'd recommend finding a good '71 through '74 core Quadrajet and send it to Rob Ross here on the board. Do NOT buy a remanufactured Chinese junk unit.
Use a 72 base 455 7042240 carb. Great starting point for any 455, 800 CFM, easily modified and relatively inexpensive. (1973 7043240 is just as good)
The numbers/stampings on the engine &/or number/code on trans would also tell you (& confirm if orig. engine/trans), which you should verify regardless, but I'd also recommend getting the report. I don't recall the VIN cutoff but in general Sloan has info for cars built into Dec. '69 & Wayne Roberts has the rest of the year so unless your car falls right in that late December timeframe that'll guide you to the right place.