Hey all! I asked this same question on FCBO, but I'd also like to get input from my good neighbors here on FBBO regarding my 440 build. Now, I know this is one of those kinds of questions that has a bazillion different answers… but I’m trying to be sensible, and not over carb a STREET driven 440 that will never see the race track or compete in any race.
For reference, my motor is a nearly bone stock 1968 440. Bottom end rotating assy is original. Has .030 pistons, stock spec cam, intake, heads etc. My car is going to be nothing but a street cruiser and highway driver. I wanted to keep my engine stock for reliability and drivability purposes.
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I’ve done my own research on how carbs move air and how much of it they move! By using a CFM calculator (because science right? LOL) to get a rough idea of what “should” be used on my application. I got 650, which seemed pretty sensible once I put everything together. Again, I’ve got stock heads, intake, exhaust manifolds etc etc. Only thing that’s changed was that it’s been bored .030 over.
From what I understand, OVER carbing a car can really hurt its performance and just how well it behaves overall. Like, if I threw an 850 on this car - wouldn’t all my power now be at the top end and the car would be a dog at low RPM’s?
My understanding is that if I were to run a bigger carburetor on this particular setup, I’d have bad drivability due to the huge ports trying to flow more air than the 440 can produce. The port velocity will slow down when the size of the ports get big. A GREAT analogy i’ve heard compares these sizes to a small garden hose vs a a big tube… one trickles and the other sprays!
Am I on the right track with my thinking? I still have folks who think I should’ve went with a bigger carb, but again - this isn’t a performance car nor a racer. It’s a practical daily driver that I want to be reliable and have great drivability. Looking forward to your insight. Learning here has always been the best for me! The carb is an Edelbrock AVS 2 650 CFM (1906)
