1badrocZ

iTrader: (1)

hey guys, im in the process of building a 383 and i need some help choosing a carb that would be a nice fit on this motor. The motor is 383 completly balanced with scat forged crank, scat forged 6" rods, weisco flat top pistons, 62cc alum. fastburn heads, lunati voodoo 60103 ( dur. 227/233 @ .050, lift .489/504), comp magnum rockers (1.52), and the rpm air gap dual plane manifold. Im looking for a holley or deman with electric choke that will work best with my combo. Do i need vacuum secondaries or machanical? What is the difference? Do i need a DP? 700 or 750 cfm? thanks!

five7kid

iTrader: (14)

First, some definations. "Mechanical" secondaries are controlled completely with the mechanical throttle linkage. Holley calls theirs "double pumper", and Demon "dual squirter" (because "double pumper is a Holley trademark).

Now, the difference between mechanical and vacuum secondaries: Vacuum secondaries are opened with a vacuum servo that receives its signal from the vacuum created by flow through the primary venturies. Also known as "demand based" secondary opening. The main benefit of vacuum secondaries is avoiding over-carbureting - which probably isn't going to be a problem with a healthy 383.

What transmission are you going to have behind this engine? The reason that is important is because you really shouldn't use a vacuum secondary carb with a manual transmission (although it can be done). If you have an automatic, you'll want a converter with enough stall to get the RPMs up into the cam's power band immediately. If you have a converter that meets that requirement, there is no way a 750 DP is going to over-carb your 383.

That said, a 4777 Holley with an electric choke conversion should do the job for you.

1badrocZ

iTrader: (1)

Thanks for clearing up that up for me! I will be running a tremic t-56 behind this motor, so mechanical secondaries would be the way to go correct? My engine builder was trying to sell me an old holley he had laying around with vacuum secondaries and electric choke, i think he was just trying to get rid of it.The 4777 is the holley Dp 650 correct? You think this is enough carb for what i have? Do you have the part # for the electric choke conversion for this carb? Im having trouble finding it

five7kid

iTrader: (14)

Sorry, that's 4779 for a 750 CFM (brain fart).

On Summit Racing - High Performance Car and Truck Parts | 800-230-3030 , it's p/n HLY-0-4779C. Choke conversion is HLY-45-224.

1badrocZ

iTrader: (1)

Alright thanks for the help, ill go ahead and order this carb and give it a try.

rjt76

you will love it. i have that carb on my 383.