Ok...now what carb??

[67GeeTeeX]

Greetings,
I just re-forged my true '67 RB 440. We went .040 over and used a Comp Cam.
cam specs. pn 21.306.4; dur @ .050, 224/224; lift .470; lobe sep 110.
I'm using an original Mopar aluminum intake that I presume was an aftermarket improvement.

I don't know if its dual or single plane, or anything else for that matter.

QUESTION; Given these details, what size/brand carb would you recommend? CFM?

I had a freebie Holley that was too tall. The car had an older Edlebrock that has absolutely NO numbers or markings whatsoever to ID it.
This is a strong street machine, and not a racer. (Well maybe a light to light sort of thing)

 

[74sundance]

Don't belive the hype

You will only about need 600-650cfm
Don't let some one tell you you need a 750cfm or bigger carb unless your going racing.

The size of a Carb for a given engine combination is "always" a compromise! The 300 to 460 cubic inch class of engines can use Carb's that range from 300 to 2400 Cubic Feet per Minute (CFM). The rather simple formula listed below will give you a vary safe CFM rating for a given size engine. This formula (and others like it) are "vary" conservative by design; Holley and Carter, Et-al recognize that a Carb that is too "small" has a better chance of working out of the box then one that is to "big". What size is right then? Between 300 & 460 Ci. on the street a Carb that is rated at 500 to 1000 CFM is going to work. 1000 CFM on a 300 Ci engine won't work! Yes I can hear you!, and your right it won't work if you just take the Carb out of the box and bolt it onto your stock engine. It can work if you have the engine combination that produce a demand that "matches the Carb". For example the 780 and 800+ CFM Rochester's were used quite successfully on engines as small as 302 CI. In general though that stock 300 cube engine will be much happier with the 500 CFM Carb. If this engine has a good set of full length headers, mild camshaft and a good intake manifold a Carb in the 650 to 750 CFM range will produce better power in the mid to top ranges of engine operation.
So there is a trend here; On the street use a smaller CFM rating on smaller displacements and the inverse on big displacement engines. There is a further trend use a smaller carb in applications where your demand for power is in the lower half of the engine operation range. There are exceptions to these trends. Many times changing a Carb to a larger one will yield more power everywhere in the power band. This brings us to the ultimate rule:
"Give the engine what it wants, not what you, your buddies, or some Magazine think it wants and you will be rewarded with power."


Engine Displacement -VS- CFM:

289 - 302 Stock 500 CFM Mild 600/750 CFM Race 750/UP CFM
351 - 400 Stock 600 CFM Mild 650/750 CFM Race 800/UP CFM
400 - 460 Stock 650 CFM Mild 750/850 CFM Race 900/UP CFM
460 - UP Stock 750 CFM Mild 750/900 CFM Race 1000/UP CFM

 

[72 Charger SE]

Your manifold is a dual plane, hence the full divider in the plenum below the carb separating the manifold into 2 halves (or planes.)

Near as I can tell, your manifold may be a reproduction of the HP manifold used on original 440 engines. You can probably find out for sure by asking your local Dodge dealer parts man, since their books should tell you not only what your part number is, but also what part it superceded or replaced.

 

[68ChargerAG]

I have always read and heard that for a mild build you should go with somewhere around 1.5 X CID for carb size. And for bigger cams and higher flowing intake, heads, and exhaust... but still streetable, to go with 2 X CID maximum. And that does match up pretty closely with the chart 74sundance put together.

 

[69 Runner]

Yup. Dual plane. I'd use an Carter AVS or an Edelbrock.

 

[67GeeTeeX]

Thanks so much to you all. I really have a good idea about what I'm going to do. The older carbs from those days are too hard for me to find, that are almost ready to go. I don't know "Pelosi" about carb tinkering. AS the holley seems too tall, although thats what I had on my original in '67. this one I have now is too tall, i'll probably find a nice EddyB.

BTW. The intake is an original alum. intake available from the parts dept at a MOPar dealer! Back then we all called stuff like this "speed equipment", as I'm sure you remember. Thanks again gents. Dave

 

[70Satellite]

I have a Holley 4160 list 3667 that is correct for 1967 chrysler 440 All trans, good core, good price for a good home.

 

[69 Runner]

That is a Mopar Performance M1 dual plane and is currently available from just about anyone who sells M.P. parts. It's an update of the Edelbrock CH-4B which (like the LD-340 and DP-4B) were available with, or without Chrysler part number

 

[Meep-Meep]

This M1 intake is closer in appearance to the factory cast iron piece and in the big picture of things there's probably little to no difference in performance. The older design CH4B has slightly larger runners and that one MIGHT extend the upper RPM limit. Also the divided plenum intake is more forgiving with larger carbs - i.e factory six pack setups on the 340 and 440. With the cam you have picked out and running in a 440 you could run a 780 vac secondary and not hurt yourself.

 

[rumblefish360]

Whilke I'm having trouble reading sundances reply, 1 long parragraph that my eyes keep reading the same line over and over again...UGH! Wheres my glasses?

His first sentence is most correct. Hoever, the rest of the engine combo and crs other equipment is something I'd like to know about.

Meep-meep is also right. You could pop on a 3310 (Holley) or a 780 like he said and be fine. The smaller carb will add throttle respons and an edge in mileage. Which is not here or there with a biog block and cam upgrades.

If you have a low gear ratio, 3.55's and numericaly lower, I'd run the smaller carb @ 650.

Carter and Holley carbs are the same height.

 

[snakeoil24]

Get your self a quick fuel carb. Go to there web site and call them I found them very help ful and they have unique quality and they also have a newly designed vac secondary that tolerates higher lift cams.

 

[dantrap]

Put a 750 Vacuum secs. or 780 on the M1 and you should be good to go.

 

[joemac1j]

I have sever stock carbs that came on 440's, 383's. Also AVS cores that I rebuild when they are needed, OR NOT.
JOEMAC

 

[rumblefish360]

I love a good working AVS and a 750 would be good on top.