OK, 950 it is, but the hp numbers on a crate 752 Hemi are 625 hp and 650 torque, which
should easily be supported by an 850, and you get the 850 benefit of better throttle
response. So, why the 950??
Most carb recommendations are way too conservative for our high performance applications. As mentioned, Ma Mopar put 750 cfm Thermoquads on their 340 small blacks.
The best rule of thumb I have ever heard and it flat out works is the CI of the engine times 2.
Example -- 340 CI = 680 cfm. That is for a pure stock application. If you start making performance modifications, you would need even more cfm in order for the engine to realize it's true potential.
My best buddy is running a 496 BB in a Dart. He started off with a six-pak set up, but it didn't perform like he wanted. I think the car barely cracked the low 12's. He then sold that set up and went with an 850 on a Victor intake and went 11.50. I still felt like after driving the car down the track that there was plenty more in the car. He sold the 850 and went with a 1050 Dominator and went 10.90's all day long. Using the 2 X the CI rule, his 496 should take 992 cfm in relatively stock form. His is modified pretty good, so the 1050 is a natural fit.
My Hemi was at 528 CI and I am running 2 Holley HP 750's on a Ray Barton crossram and there is instant throttle response with zero hesitation and it idles all day long. I will soon be at 572 like the OP and I have 1500 cfm with no issues. Big CI motors have to breath and it makes no sense to use a small carb as a choke point... 0.02
