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1974 DCH 340: Which Power Valve & Fuel Fitting to use?

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Parts manual calls for a #41, but all I have are a #43 and a #47. 

  • #43 has a larger orifice than the #47, so I'm thinking the larger one is for an L20. 
  • #43 is OE for the California L20
  • #47 is not used in any engine.

EUREKA - ANSWER:  The #47 is actually a #41 - they really put a big "barb" on their "1" character!  Taking all the time to document this and post put this info "in my face" long enough for my haphazard brain to realize this!  I saw this "barb" on the #100 Main Primary Jet - original interpretation was it was a #700, but on the Power Valve, the "barb" is even more pronounced.


(I'll leave the rest of the discussion here for entertainment while the table provides some great info.  I should probably post a thread "DCH340 Jet and Power Valve OE sizes Table" since I've never encountered this info anywhere.  It could also be expanded for all the numbered jets, bleeds, and emullsions.)


To make matters worse, my 74 is a CA variant and there are no CA carb variations in the online parts manual.  I suspect because 74 was a bastard year, there are and they did not find their way into the parts manual.


However, there is evidence to suggest that larger numbers means smaller orifices:


ASSUMPTION:  CA version are run leaner and have smaller jets


The Primary Jet is #99, the CA version is is #101 (the Canadian is #108 ! )

The Power Valve is #40, the CA version is #43  (the L18 is #41)


Here is a table of values I've extracted for the 4 carb variants from the online parts manual:




                L16 early   |------L16 late--------|     L18      |---------L20------------| 

                                                            NOTE:  (65) denotes # in picture

Power Valve:      #50(65);                   #53(64);   #41(62);             #40, #43-CAL(64)
Main Jet (pri):  #112(57);  #97.5-7211, #98-7212(57);  #100(55);  #99, #101-CAL, #108-CAN(56)
Main Jet (sec):  #155(58);                  #170(58);  #170(56);                     #160(57)
Slow Jet (pri):   #48(59);                   #48(59);   #45(57):                      #48(58)

Slow Jet (sec):  #180(60);                   #90(60);   #90(58);                     #100(59)






I have two types, Small bore banjo ID and Large bore banjo ID.


The Small fits the needle/seat nicely, but the fuel strainer protrudes out the  top, sitting of the lower banjo flange instead of the n/s face.


The Large is uber sloppy on the n/s and can be significantly offset when fastened down.  (It is clearly way offset visually - 1/16" or at least 1mm offset.  NOTE:  the fuel strainer stacks properly.



I realize these are technical questions, but I feel like a paleontologist with a box of bones here!


Thanks in advance for any help,


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