225 Modified Slant

I guess it should also be pointed out that a 4bbl often adds only about 10% power to the engine on a streeter. And contributes very little to the making of torque, below the torque peak.
So if you build a 200hp slanty, you can expect 20hp at peak output. The 4bbl power will build from just measurable before the torque peak, to maximum at the power peak, and then it will help to sustain the power a bit longer over the top.So even tho the secondaries double the butterfly area, the airflow volume through the primaries reduces as the secondaries open. So if your engine can only inhale 300cfm,then,whether you have a 390cfm carb or a 500, or a 650 will not make it go any faster.
But, you might ask; if it can pull all of those 300 thru the primaries,what is the point of even having secondaries?
>Well, for one thing Smaller primaries make the engine more driveable. The signal thru the boosters is sharper and is faster to be activated, requiring less band-aiding from the accelerator pump.
If the primaries get to be too big, then every little movement of the gas pedal produces a large throttle change and the engine gets to be jumpy.
If the primaries are too small, then they might be always opening far enough to activate the secondaries, and smooth acceleration gets to be tricky.
There is a formula to help you size your engines needs. It looks like this;horsepower times RPM divided by 3450.
So in the above example 200hp x 4800/3450= 278 cfm. If you have an automatic and have to rev it 15% higher to put down the maximum average hp, then the revs will go to 5500, and the required cfms will be 200x5500/3450=319cfm. Typically these are minimums.
>A small 4bbl is better than maxing out a big 2bbl. Why? Cuz the smaller butterflies of the 4bbl are more driveable at normal rpms. They will be less jumpy, and require less pumpshot to cover sags. And just maybe you can tune the primaries a hair leaner for a bit better gas mileage, and fatten up the secondaries a hair,to average it out.

EDIT
If you put that 650 on your slanty that only can pull 319, then it will be a 319. I guess that is what I was trying to say