'56 Fuel Pumps, Judging - NCRS Discussion Boards

'56 Fuel Pumps, Judging

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  • Don Owen

    '56 Fuel Pumps, Judging

    I have two correct stamped 4262 AC Fuel pumps. Both are similar, except for the bottom plates. One has the"AC" cast in the center with two screws 180 degrees apart, the other is plain with a single screw in the center.Also the fuel fitting port locations are quite different. Looking down in the mounted position, the "AC" one has fittings at 11:00 and 5:00. The plain one is about 4:00 and 8:00 One judge told me he likes both, having seen original engines with the plain bottom plate. I prefer the other one because its in better condition, has the correct GM gaskets, and the fitting locations make more sense. The top casings on both pumps are the same-- 4262 stamped on the right mounting flange and "AC" cast on the top.


    My car is an early '56, No.336, which certainly affects many parts on the engine.


    What do you think? Thank you so much for any feedback.
  • James F.
    Very Frequent User
    • December 1, 1985
    • 596

    #2
    Re: '56 Fuel Pumps, Judging

    Don, You could not have ask a more timely question. I am currently working on an article regarding the 4262. The single bolt pulsator cover is the correct style for the 4262. Somewhere along the line someone replaced the bottom casting with a double bolt pulsator style cover. It is not correct. The bottom casting should have cast"Made in USA" also, "AC" and "RP". I don't quite understand your inlet and outlet arrangement. Here's what it should be. Looking down on the mounted pump and the mounting flange at 12:00, the inlet should be at 8:00 and the outlet should be at 4:00. You should see three screw bottoms between these two openings. Your 4262 should have one vent hole (firewall side) on the top casting. The 4262's use a small diameter, shorter push rod return spring than the later AC fuel pumps. I believe these springs promote push rod float at high RPM's. All 4262's used the 5/16" steel gas line. Regards,

    Comment

    • Don Owen

      #3
      Re: '56 Fuel Pumps, Judging

      Dear Jim: Nice to hear from you. We met at Seven Springs and maybe Carlisle a time or two. My '56 is almost finished...if there is such a thing.


      She does look pretty and we plan to give it a shot in Bowling Green this summer. Hope to see you there!!


      Anyway, My message is a little screwed up in that I meant to say the fittings should be at 8:00 (inlet), and 4:00 (outlet).That makes more sense with the shape of the fuel lines. I guess I'll go with what I had along, although I don't think the bottom plate (with one center screw) has any stamping at all. There is some surface rust which led me to find a nicer one in the first place!!!


      Meanwhile, my incorrect replacement does have the correct gaskets-- the upper one has the little tab, and the bottom one has the white stitching, which is " quite visible and a judgeable item ", according to Dr. McCagh!!!Learning about these darn gaskets also got me going on improving my fuel pump.


      Do you suggest just pirating the gaskets from the two screw "AC" pump?


      By the way..I do not have a correct brass elbow fitting. Do you or someone you know have one or any info on these little critters? Current repros are not close enough so I'm just waiting to get an old one.


      Jim, best wishes to you and yours in the coming year! Don Owen

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