shipma2

i am thinking i want to upgrade it to a double pumper 750. will a 750 flood a 454? ive heard from some it will but i dont think it will. would a double pumper holley be good on a truck setup? or a truck avenger? help please i belive the 1405 on it is to small a cfm

maxxman04

in all my years, yes, a 1405 is too small. having said that, my boss claims a 650 cfm on a 460 that tows heavy, no problems. i call bs, but he swears. typically a big block does need the higher flow to run properly. a 750 is usually good for a big block. some higher output big blocks ran an 850 from the factory.

slw210

cubic displacement divided by 2 (ex: 454=227)
maximum rpm divided by 1728 (ex: 6000 rpm=3.47)
multiply those two figuires (ex: 227 x 3.47=787.69 cfm)

Hold on we are not done. You now have to factor in volumetric efficiency. A Nascar race engine runs at 85%-90% volumetric efficiency. A normal street car wil be 75-80%, depending on what you have done with your heads and exhaust.
Ex: 787.69 x 75%=590.77cfm

The formula works, you may need to rejet and make adjustments to fine tune.