I`m running a fairly healthy 350(see sig) in my car and was wondering if a 650dp was big enough for it. I talked to a reputable engine builder who dynos his engines and he said
a 375hp 350 really needs a 750.I do have a 750vs carb that I
had rebuilt but the throttle response just isn`t there and it has
a slight hesitation at low speed acceleration.I have already bought larger pump shooters and I`ll probably need to buy a
pump cam kit to get this thing to work.I took off the 750 to
do these changes and I put a 650dp that my brother-in-law
had kicking around.Well the car seems to love it,throttle response is excellent it pulls really hard to 6000rpm in 1st and 2nd I never
took it that high in 3rd.My question is am I getting all the power
I can with this 650 or should I take my time and try to sort out the 750?

 

My experience going from a 750 VS to 650 DP on the 396 was no decrease in MPH (indication of HP), and an ET reduction of .2 sec. When I converted the 650 to 750 via the Proform main body, no noticable difference.

People tend to overcarburate. The good news is it usually doesn't hurt them.

 

Except perhaps in mileage in a double pumper.

 

if you already have a 650dp, your fine. And as five7 alluded to, if you want, you can buy the proform mainbody(costs $100 IIRC) and is rated at 750 cfm.

but i would stick with what you have.

 

If this is regularly street driven, you probably don't want the Proform because it eliminates the choke. The guy I got the 650 from had already done that to it, so I didn't lose anything there (the 750 VS still had the choke, though). A choke is kind of nice when you are starting the car cold and have to be somewhere.

When I said over carbing doesn't typically hurt, I was thinking primarily in terms of WOT powerband. As Apeiron said, economy can be affected, and the throttle response you noted will also be "mushed up" a little with a larger than necessary carb.

 

A little bit ago Chevy High Performance did a little test between the different carb sizes, working against that "bigger is better" thing. The engine was constant and they list the parts used to build it [the engine].

<A HREF="http://www.chevyhiperformance.com/techarticles/148_0403_choose/index.html">Here's the article</A>. Any changes that they made to the engine/carb they noted. They also list the jet sizes they use and what not.

Kept me busy for a few hours.