Aussie66Fastback

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Aussie66Fastback

so how does one be assured that carb is
1) right size
2) set up correctly for best performance?

67mustang302

True to a degree. Carb's end up being a compromise to some extent for throttle response. A well tuned pump curcuit will have excellent throttle response if the induction velocity is high, since the air/fuel will be rapidly delivered to the cylinder. But the higher velocity comes from a slightly more restrictive system, meaning top end will suffer to some extent. As long as the setup isn't toolarge then lower rpm throttle response should be just fine, and vaccuum signal should be pretty much instant. It's the larger setups that cause the poor response at lower rpm. My throttle response is pretty much instant at any rpm over 1,500, but I'm only running a 570cfm carb. The problem with carbs and throttle response is that as the system moves towards favoring the higher rpm, the power and response in the lower rpm drops off. FAST. The newer engine management systems can also run insane amounts of ignition advance to get excellent throttle response, and as soon as the knock sensor triggers it just pulls timing out. The biggest advantage of a carb though is cost, you can build a setup that maybe loses some on the bottom end, and lacks a bit of low rpm throttle response, but use the money saved by having a setup that builds more power up top, and be faster for the same amount of money.

I like carburetors for a lot of reasons, but if I bought a new car, converting it from EFI to carb would about about #50,000 on my list of things to do to it, right behind making it look like that dogmobile from Dumb and Dummer.