Hey Guys, Can I get away with using the carb off of my 400 engine for a mildly built 455 (small cam, some head work, and bored .040 over) using the stock 67 intake? If I need to run an 800cfm quadrajet, can the throttle plate from my 67 400 carb swap over to a later 800 cfm? I want to retain the switch pitch throttle shaft hook up... Thanks for the input. Dave
Sure - An 800 would be better, but all 70 455's came with 750's. You might need to jet up or change air bleed sizings, but thats just fine tuning.
Keep in mind the Q-jets are calibrated for the engine line they were used on. Can you get away with it, sure, just don't expect it to run it's best. Mild cam or not, most Q-jets need work on the idle system for them to idle well. All Q-jets, 750 and 800 CFM use the same 1 3/8" primary throttle blades. The 800 has a larger outer venturi giving it more capacity. I would say you can swap the primary throttle shaft to the later 800 carburetor.
You can definitely swap baseplates on an 800 71+ CFM body, just be aware of any idle air bypass holes on either. I have a carb set up this way with a 67 base on a 73 body.
