carb recommendation for a street 440?

[madmike]

I have a 'supposedly' rebuilt 440 in my '68 Charger (it came with the roller car), so I don't really know much about it (I have no receipts).  It does have a smallish cam (284 duration, 484 lift, by pn it is a Comp Cams Magnum 280H), an Edelbrock Performer aluminum dual plane intake, and when I run a small screw driver through the spark plug hole, I think I can feel a slight upward (not dished) dome on the piston tops.  If they are not domed up, then they are at least a flat top, so I'm guessing a minimum of 9.0 compression ratio.  It will have electronic ignition.  The car is an A833 four speed, with a 3.23 geared rear.

My buddy is trying to convince me to use a 750 (even 850) cfm Holley mechanical double pumper on this engine.  From everything I've read, that seems like to much carb, for a heavy, highway geared car.  It seems a vacuum secondary set up would perform better, and maybe even be easier on gas (not that I'm worried about mileage).  I don't mind using more gas, if I get more performance out of it.

What do you guys think, what would be a good carburetor to run on this car?

[Cooter]

Depends on what you want the car to do out of the hole as to whether or not the Double pumper is the ticket or not...I'd stick with the Vac, secondary if that's what you like, but I'm running bout the same engine, with a little more cam, and love a Double pumper...Mine is of the 700 CFM flavor...

[madmike]

Cooter,

I guess I'm just looking for a decent all around performing carb, for my existing combination of parts...  I'm not sure I'll have much 'out of the hole' performance anyway, with such a heavy car and 3.23 gears...

But, I've never owned a big block Mopar either, so maybe I'll be pleasantly surprised...

[Cooter]

Well, you got those that will argue the 440's came with 850 CFM TQ carb's and the SIX PACK @ 1350 CFM and such, but comparing a speadbore Thermoquad to a Holley 850 Carb is Apples and Oranges...Sure, the 850 TQ might perform GREAT oin your 440, but a Holley of the same size might be too much for it...Remember, Holley is THE Heart and Soul of Performance...Period...

The fuel curves and delivery systems are much different between the two carbs...

[Nacho-RT74]

everything depends IMHO more if vacuum secondaries or pumped and maybe not REALLY the CFMs rate ( what doesn't mean is something to jump out )

Honestly and as far my analysis ( what doesn't mean is a correct one ), for street use, vacuum secondaries are better and enough. An incorrect set on pumped secondaries will get you rich mixture so then, failures related. Vacuum secondaries are harder to get that kind of failures and are more free of some kinds of adjustments.

Experts will chime on this better than me, but just my personal opinion.

[BigBlockSam]

 

[BSB67]

I would probably stay away from a 850 DP.  You should be fine with a 750 DP and dual plane intake.  That is what I would pick.

[ACUDANUT]

 Holley 750 double pumper..!!... Vac. Sec. work better for a auto trans.

[Sixt8Chrgr]

I have a similar build with a Holley 650 double pumper built and blue printed by a custom carb shop in Mooresville NC. Car runs great.

If I had to buy a carb from Summit or the likes I would probably go with the 750 vacuum secondaries.

[daveco]

I ran a 750 double pumper (4779 iirc) on a torker intake. Auto, stock converter, 3.23s.  Medium to mild cam (don't remember the grind, but it was a D.C. "purple shaft" had a nice lumpy idle) 440 69 Charger. Ran great.
Definitely not over-carbed.

[elacruze]

Holley 750 double pumper..!!... Vac. Sec. work better for a auto trans.

With the stick shift, I'd go with the 750 holley DP. Even if you could use the 850, you won't miss it but with the 850 you may miss a little drivability down low.
If you really don't care about what it looks like under the hood, my favorite carb is the Quadrajet. Although with the stick you don't need vacuum secondaries, the Q-jet is very easy to tune and has awesome fuel mileage potential. Drivability is second to none. Of course you need a spreadbore manifold to run the Q-jet.

[Brass]

No expert here by a long shot – but I don't buy the premise that mechanical secondaries are for sticks.  I've had 2 vacuum carbs and 2 mechanical ones on Chargers with autos and 3.23 gears.  Both cars had converters with some stall but I don't think that factors heavily.  In any case, from a "seat of the pants" perspective, the mechanicals are way better.  They have an aggressive acceleration curve, less hesitation, and there is no doubt when they open.  Also, a smaller carb will provide a snappier throttle response but will run out of air up top before one with more cfm will. 

I use a 700 double pumper but the 750 seems to be a good, tried-and-true performer for most 440's.  You might also consider doing a search on here too for more info.

[flyinlow]

750 vac . secondary Holley runs well on my 440 Charger when I used it. Tried a 650 spreadbore, mechanical sec,DP on the Charger. It ran well, good throttle responce. Both Holleys ran rich so you don't need to hook up the choke.

I have always liked the TQ and Qjet for street use. The problem with these carbs is the development stopped 30 years ago on them and tuning parts are hard to get. Holley style carbs have continued to be improved.

[John_Kunkel]

I'd go with a 650 for driveability and throttle response or a 750 for performance.

[ACUDANUT]

750 dp.  650's are too small for a big block.

[Cooter]

 The 440 came with a 625 Carter AFB in 1966-'67?...The AVS was around the same CFM IIRC...

[BSB67]

The 440 came with a 625 Carter AFB in 1966-'67?...The AVS was around the same CFM IIRC...

Current discussion on Moparts on Carter AFB/AVS cfm ratings.  Despite the 625 and 750 ratings (383/440) some argue that they really don't really flow that @ 1.5" Hg dP.

[firefighter3931]

A 750 DP is what i would use 


Ron