[Chrysler300] CARTER AFB Capacity Calcs

["Richard Barber" <c300@xxxxxxx>]

I received or retrieved the information below from some one, sometime and
warn that it is not consistent and may result in more inaccuracy being fed
into the system.  That being said, I have played with the data and converted
the 625 cfm carb primary venturi to 1/5/16" for consistency and determined
the chart is based on about 100 cfm per square inch of total venturi area.
I think several of the bore diameters are off, also, but I believe nominal
carb capacity is more likely to be based on venturi area.  

I'm working on a pair of Carter 2444S/2445S carbs for a '56B and the
venturis are both stamped 1 1/16" and the throttle bores all measure 1
5/16".  Based on the four 1 1/16" venturi openings and the nominal 100
cfm/square inch of venturi area, each carb might be rated at 355 cfm.  The
354 cid '56B engine requires 533 cfm at 5,200 RPM at 100% volumetric
efficiency or about 75% of the total air capacity of the two carbs.  Seems
reasonable.  533=(354 X 5200)/(2 x 1728)

These are the same carburetor dimensions specified for the 1955 331 cid
C-300 engine.  Interestingly enough, the New Yorker and Imperial single four
barrel carburetors also had the same dimensions (and jets) according to the
specifications in the 1955 Service Manual.  So, adding the second carburetor
doubled the nominal air capacity, although the requirement only went up 13%
(from 4600 RPM to 5200 RPM).  Those two 2317S's or the 2444S/2445S pair
should really feed those old hemi's.  The net effect would seem to be a
slightly higher manifold pressure at any given throttle opening due to the
velocity being halved by the addition of the second carburetor.  And, that's
a good thing for more power, but bad for power brakes.  Anyone heard of a
reasonable or rated redline for the 1955 300 and/or NY engines?  Are these
six-grand engines in stock form?

A possibly helpful hint for calculating total venturi area: (This gives the
area for two venturis-D is in inches)
Primary venturi area:  1.57 X D squared 
Secondary venturi area:  1.57 X D squared
Add the two values above to get the total venturi area per carburetor,
multiply by 100 to get an approximate carburetor air capacity in cfm.

I know there are some other engineers, mathematicians and technicians out
there who will check my calcs and I hope they do so.  If anyone has
comparable capacity data for new or aftermarket carbs with specified venturi
diameters it would be interesting to see how they stack up against this rule
of thumb.

C-300'ly,
Rich Barber
Brentwood, CA
1955 Chrysler C-300

The information below was received or retrieved from an unknown source and
contains some apparent inconsistencies:

To determine Carter AFB carb flow, measure the butterfly bores and use the
table below:

CFM       Venturi Diameter            Bore Diameter
            primary    secondary       primary   secondary
--------------------------------------------------------
400	1 1/8          1 1/4           1 7/16      1 7/16
500     1 3/16         1 1/4           1 7/16      1 11/16
575     1 1/4           1 9/16         1 9/16      1 11/16
625     1 3/16         1 9/16         1 7/16      1 11/16
750     1 7/16         1 9/16         1 11/16     1 11/16

 

9000 Series AFB Code Deciphering

Base part number is 9000 and the last three digits refer to flow rating. For
example, 9625 is a 625 CFM AFB carb. Adding 0, 9625 means it was set up for
a Chevy style linkage, adding 1, 9626, means it is a 625 for a Chrysler,
adding 2, 9627, means it is for Ford; adding 10, 9635, means provision for
EGR.

If the carb is an aftermarket version, it will have a 9xxx cast in the front
near where the mounting stud goes through.


-----Original Message-----
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of mgoodknight@xxxxxxxx
Sent: Friday, November 13, 2009 4:38 PM
To: LUCKYL46@xxxxxxx
Cc: Chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] CARTER AFB

Hi All,
It always surprises me how much incomplete (sometimes erroneous) information
gets printed.  My Carter info sheet only shows this 3108s carb to be used on
'61 New Yorker  413 engine.  Other searches on my literature have seemed
similarly incomplete, but it least this supports the idea that it is mostly
if not only a 413 application.
Marshall

---------- Original Message ----------
From: LUCKYL46@xxxxxxx
To: Chrysler300@xxxxxxxxxxxxxxx
Subject: [Chrysler300] CARTER AFB
Date: Fri, 13 Nov 2009 13:19:18 EST

  
HI GANG. CAN ANYONE TELL ME THE CFM FOR A CARTER AFB#3108S. OR POSSIBILY 
WHAT MOPAR IT IS FROM. THANKS JOE LUCIANO QUEENS NEW YORK.





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