The thing that concerns me is that the original application was such a large displacement engine. This means that the idle feed restriction may be too big and the carb will run rich all the time (like running a Holley 3310 on a 350, but worse. The 3310 was set up for a 396. The disparity here is much larger.). This is why I sourced my carb from a 1979 Chevy van with a 350. I would also suggest using a carb from a 1976 or newer BOP 350 application. The Caddy and Chevy apps use the side inlet, while the BOP's use front inlet. Plus, since the computer Q Jet is essentially a computerized 76+ carb, the linkages and hoses will all fit as if it were factory.
Also, remember that richer is not necessarily better. A mixture that is too rich will not run as well as one that is leaner. This is because the latent heat of vaporization of the excess fuel that is not burned will take heat energy out of the combustion reaction. The optimal Air:Fuel ratio for economy is around 14.7:1, and for power it's around 12.7:1. If you tune the carb on the lean side in the primaries, it will be better around town. Then you can put the secondaries slightly rich for the rare times that you need them. Remember that 99% of your driving will never engage the secondaries, so it is the primary metering and tuning that will net you the greatest benefit while driving. Also, do not set up the secondary air valve to come in sooner than the engine can use the extra air, or it will just bog. Improper setting of this adjustment is why some call them the Quadra-bog. More is not always better than less. Tune the secondaries to provide only what is needed, and no more. This will give you the crisp throttle response a Quadrajet is capable of without the transitional bog that curses adherents of More's Law ( if a little is good more must be better!).
Also, remember that richer is not necessarily better. A mixture that is too rich will not run as well as one that is leaner. This is because the latent heat of vaporization of the excess fuel that is not burned will take heat energy out of the combustion reaction. The optimal Air:Fuel ratio for economy is around 14.7:1, and for power it's around 12.7:1. If you tune the carb on the lean side in the primaries, it will be better around town. Then you can put the secondaries slightly rich for the rare times that you need them. Remember that 99% of your driving will never engage the secondaries, so it is the primary metering and tuning that will net you the greatest benefit while driving. Also, do not set up the secondary air valve to come in sooner than the engine can use the extra air, or it will just bog. Improper setting of this adjustment is why some call them the Quadra-bog. More is not always better than less. Tune the secondaries to provide only what is needed, and no more. This will give you the crisp throttle response a Quadrajet is capable of without the transitional bog that curses adherents of More's Law ( if a little is good more must be better!).
