Whats the difference ? 4150 question !

33IMP said

Agree with PRH, marketing strikes again. Holley came out a while back with a new hi-zoot carb that they called a (something) 950., hoping the customer would assume it was a 950 cfm carb. It had the same throttle size and venturi size as a 750. Cause it WAS a 750. The 950 name was marketing.

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Actually..... it’s not a 750.

Before the “HP” carbs existed, a very popular carb in the circle track world that was sold through a bunch of different carb modifiers was to take a 750DP, cut the choke tower off, blend the top, then taper bore the bottom of the carb body from the stock 1-11/16” up to 1-3/4”, and then use an 850 baseplate on it.

The HP950 is basically an ootb version of that concept, only with an improved air entry shape.
The flow about 860.

A “750” has a 1.375” venturi/1.687” throttle bore.
The original HP950 has a 1.375”venturi/1.750” throttle bore.