Whats the difference ? 4150 question !
So, anyone got any thoughts on what a garden variety 4779 / 750 might flow with and without the choke tower?,...thanks
IIRC, it doesn’t flow much more if any at all with the choke tower off.
What it does affect is driveablity. A nebulous term for sure, but it is a “a thing”. If you look at a carb with a choke horn on it and the air filter base and filter sitting on it, you can see that the choke tower blocks off a big section of the filter. So the air coming in through the filter has to hit the choke tower, go vertical, then make a 180 degree bend to get into the carb.
Air does not like to bend more than 7-8 degrees before it starts getting real turbulent (I’m sure there’s a Reynolds number for it but I don’t know what that is), remembering that the flow won’t be laminar.
I’ve said before I don’t get too excited about CFM ratings. They are a buckshot accurate guesstimate of what a carb CAN flow at 20.4 inches of water.
You can put a 4779 on a 273 and it will flow “X” amount of air. Take that same carb and mount it to a 540 and it will flow “Y” because the bigger displacement will generate a greater pressure drop.
Of course, if we are discussing pumping losses, the bigger carb always wins that, up to the point you lose booster signal and the fuel curve gets shot to hell. Of course, there are boosters that will generate a much greater signal at lower air speeds through the booster...but what about the fuel curve at higher RPM?????
So there is that.
