Is a 650 carb what I want?

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70DartMike

70DartMike

Too many projects
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I've got a built 340, 10.5:1, Edelbrock RPM High rise intake, X heads, 1 - 20-232-4 Comp Cams Camshaft (not sure on specs..), 727, 3.23 rear, which is just going to be used on the street. I'm not planning on racing it anytime soon. I need a carb recommendation. I've got a Holley 750 double pumper which I got for free. I rebuilt it with a non Holley rebuild kit, andddd now it leaks. Also, a check valve is torn, and it was pretty gummed up inside.
I am going to buy a new carb, and right now my parts store has a pretty good special on Holley carbs. Is a 750 too big for this motor?
The carb size calculation of CID x Max RPM / 3456 says I should be using a 600 CFM carb, which seems a little small, but I don't need to be running an oversized carb either.
Is a 650 too small? Or is that pretty much what I want? Also, do I want a double pumper? Or is that more a 4 speed application?
 
For the street, a 650 would be excellent to use. The difference between the two carbs is probably only 10 HP or so at best.
4spd cars enjoy a double pumper more so than a automatic car does . It is possible to use a DP. The issue concerning the use of a DP vs a VC carb is timing of the secondary opening. With a DP, all the control is in your foot as to when the engine can use all the barrels open, or not.
The VC carb will it for you. You can tune the carbs secondary side a bit with different parts from Holley.
If it an AFB carb, tuning the secondary side is mostly out. Possible, but a huge pain if it needs
To be delayed.
If it is a AVS style carb, the air door is tuneable with a screwdriver for quicker or slower rates.

Considering the partslistes, I myself would go with a 650 AVS.
 
X2

rumblefish360 said:
for the street, a 650 would be excellent to use. The difference between the two carbs is probably only 10 hp or so at best.
4spd cars enjoy a double pumper more so than a automatic car does . It is possible to use a dp. The issue concerning the use of a dp vs a vc carb is timing of the secondary opening. With a dp, all the control is in your foot as to when the engine can use all the barrels open, or not.
The vc carb will it for you. You can tune the carbs secondary side a bit with different parts from holley.
If it an afb carb, tuning the secondary side is mostly out. Possible, but a huge pain if it needs
to be delayed.
If it is a avs style carb, the air door is tuneable with a screwdriver for quicker or slower rates.

Considering the partslistes, i myself would go with a 650 avs.
Click to expand...
 
The parts store had a Holley 670 Street Avenger on sale, which is what the guru's there thought was my best choice for the price I have to work with.
 
70DartMike said:
The parts store had a Holley 670 Street Avenger on sale, which is what the guru's there thought was my best choice for the price I have to work with.
Click to expand...

There are usually 2 camps of carb lovers...

1. Holley guys
2. Carter guys

They usually recommend what brand they like (or maybe which brand makes them the most money).
 
Thanks Sedan, 65val. I did recommend the carb of MY choice didn't I?! LOL!
The CFM recommendation sticks, maker of carb be damned, what ever your choice is, you have to be good with it.

The extra 20cfm of the Holley Avenger should be ignored. That carb would be just fine up top. IDK where they get the extra CFM from, but it'll perform nicely IMO.
 
just put the holley street avenger on my Dart , works great , unfortunately smoked the diff on my first run . Holley street avenger works really well , right out of the box it ran better than the carter .
 
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