alright so ive decided to get rid of my vacuum 2ndary holley 750 and go to a mech secondary on my 383 since it pulls about 4 lbs of vacuum. going from this ive decided already its going to be a demon carb,

now should i get a 650 or a 750 to put on it.
the motor is a 383 with dart pro 1 aluminum heads, performer rpm intake, com cam 490-506 lift, it makes power from 2800-6400 rpms and has a 2800 stall on it.

im not sure if i am going to need a 750 or if i should just get a 650 and jet it up a couple

what do u think

 

My friend who owns a Chevelle has a 650 Demon, and told me that Demon rates their flow to include fuel, as well as air, so a 650 Demon is the equivalent to a 750 holley.

 

ok yeah i heard demons flow way better thats why i wanted to get one of those.

 

He's happy with it, although we had a problem getting his fuel fittings to seal properly. I have heard other's say they found metal shavings inside the carb when pulled out of the box brand new. I'd just be cautious and search it over carefully for anything of the like.

 

i'd go 750 DP..

 

A 650 Demon doesn't flow as much as a 750 Holley. More like 675.

Holley is now rating some of their carbs "wet" as well.

A 650 DS will be faster in the quarter than the 750 VS was (at least, that was my experience, by about 2 tenths). But, a 750 DS would be better for a 383.