gekko13 (5/10/2011)
[quote][b]
Flow ratings for carburetors are measured at a pressure drop of 1.5 inches of mercury for 3 and 4 barrel units and 3.0 inches for 1 and 2 barrels. So, to compare a 150 cfm Holley 94 to a 4 barrel, you have to multiply (the cfm) by .707. That equals about 106 cfm. 106 cfm times 6 equals 636 cfm. You can see that the maximum flow is not that much as compared to a dual quad set up.THANKS gekko13! While I've known that two barrel carbs were rated at a different pressure drop than 4 barrel carbs, I never was clear as to how to compare their flow ratings.
Going a bit further with this issue, the Holley 94 was upgraded over time using different venturi sizes and different venturi enhancements. The
Ford EBU6 carb (
Holley knock-off) used on '56 Fords had 1 1/16 venturis, 1 3/8 throttle plates, an automatic choke, and annular (?) style venturi boosters. They were rated at 245 cfm.
For those of us fiddling with 3x2 set-ups, your multiplier tells me that using one of these would flow ~173 cfm (in four barrel language) and the three together would be rated at ~520 cfm when put together. Six together would be 1,039 cfm!?! My recollection is that the '57 teapots were rated at 330 cfm each or 660 on a 2x4 set-up.
While a good four barrel is perhaps the best way to go performance-wise, especially with John Mummert's new manifold, I love the looks of the multiple carbs, air cleaners, and the linkage!
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York