Hello, This is an ignorant question, but I hope someone can help me. I had a 1974 455 Buick engine rebuilt. It didn't have a carb on it when bought. I bought a 7042240 carb for it that was advertised as rebuilt, but turned out it was missing a bunch of internal pieces and had some broken parts. I then bought a Qjet 7045240. The question I have, is the engine builder says this carb has a different choke than the manifold is set up for? Anyone have suggestions on what needs to be done to make this carb work for the 1974 engine? Thanks, Rich
The 1974 carb is a divorced choke carb, that works off a choke coil in the intake manifold. The 1975 carb was a hot air choke on the side of the carb. If you want to use the 1975 carb, convert the choke to electric function. The black plastic cap on the choke housing is removed and replaced with an electric unit. Quadrajetparts.com has the part you need. Once installed and set, all you need to do is provide the choke unit 12v off a keyed ignition source.
The 75 Quadrajet is not a good design. You are much better off with the 7042240 unit. 71-74 were the same and parts will interchange. The 75 unit was a one year design. It had hot air choke, which is fine, but the internal passages were different. It had an aderoid metering rod designed to compensate for fluctuation in altitude and pressure. I have plenty of used parts if you know what you need. I can also build you a nice Quadrajet.
Thanks for the responses. I am set on using the 7045240. The carb is the thing holding everything up on the car and the 1975 carb is good to go except for the choke issue. I checked Quadrajet Parts.com and they have a conversion kit for 1968-1974 Qjet only. I saw one on Summit that says it is an electric choke conversion kit for any Qjet that has a heat tube style choke. Would this be the one I am looking for? Thanks again for the help. Rich
We sell a good USA made E-choke conversion for the later carburetors. It will fit the 1975 and newer Buick Q-jets. Install is minutes, just remove the hot-air choke, block the vacuum supply to the housing (90 percent of the folks doing this conversion forget to do this), install the E-choke and done. We also supply the electrical connector for it.......Cliff http://www.cliffshighperformance.com/parts.html
This one:http://quadrajetparts.com/electric-choke-thermostat-rochester-flat-terminal-p-416.html You just install it in place of the black plastic cap.
without hesitation I would send cliff the carb for testing. advertised rebuilt leaves too many possibilities for failure. good luck
We provide a testing service for carburetors that folks have purchased from Ebay and other sources claiming to be "rebuilt". I would actual advise against sending it here, unless you plan on spending some money on it. 99.9 percent of those shiny Ebay and other on-line sourced units advertised as "rebuilt" or "remanufactured" aren't worth two squirts of duck poop, many heavily modified and often "butchered" beyond easy repair. I'd rather start with a "virgin" original unit that is unmolested, and for sure as Mark mentioned avoid the 1975 and early 1976 units with the aneroid located APT system. They can be made to work OK, but the internal passages cross connect the main system and are clear down in the bottom of the carburetor where all the water, corrosion and debris settle over decades of use. We avoid them here if at all possible......Cliff
Rochester tuners that really no how one works are a rare breed in 2016, and I bet most anyone that does drives a Buick. Or Pontiac.
