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57 - 58 supercharger bonnet differences and why?

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  • Fuel System: 57 - 58 supercharger bonnet differences and why?

    I have noticed the bottom plate of the bonnets on the 57 and 58 Golden Hawks is different. The 58 has a tube to drain any excess fuel which might accumulate there. It is not found on the 57 models. The 57 models have two holes which are closed by flappers when the super charger is operating. On the 58 models the bottom hole is plugged. In the added picture of a 58 Golden Hawk the vacuum port goes through that hole.
    I am wondering why only one hole is used in the 57. Should I plug the bottom hole in the 57 and add a drain. I am assuming the 58 changes were made for a reason -improved supercharger performance?

    Another difference is the location of the fuel line coming up through the bottom of the plate near the drain tube.
    Attached Files

  • #2
    This will explain the changes to supercharger air chamber from service bulletins. "The fuel and modifier lines also have internal connections from air chamber base to carburetor"(from service bulletin covering new 1957 model features ). My Clipper was made 1/25/57 has these features
    Attached Files
    Last edited by acolds; 01-09-2019, 05:47 PM.

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    • #3
      All the '57 GH's I have owned, seen and worked on, all had the tiny excess Fuel drain tube from the bottom right front corner of the Lower Air Box half all the way down the timing Cover to below the Oil Pan. So it must not have been a '57 to '58 change, but an early to Late '57 one.
      StudeRich
      Second Generation Stude Driver,
      Proud '54 Starliner Owner
      SDC Member Since 1967

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      • #4
        the flapper valve patent is @: http://pdfpiw.uspto.gov/.piw?PageNum...3DPN%2F2756735 . There are a couple of notes in the chassis parts book about the drain tube and flapper valve.
        Mike

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        • #5
          Thank you all for responding. Al - your post made me remember that the previous owner had included some service bulletins which I found. SB #320 is the one you posted and it mentions that both vent holes (base and cover) were plugged and the drain installed to vent and drain the air chamber. Interestingly SB#325 indicates that later air chamber covers had no vent holes and a cure for hard starting of hot engines was to drill a 1" hole and install a flapper on the side of the cover.
          Mike - where do you see the notes on the vent fitting and tube? I do not see them in the "super charger parts" section of my manual.

          After reading the information I am inclined to plug both vent holes and install a drain in mine. What are your thoughts on this?
          Anyone have more information on the size of the drain tube?

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          • #6
            Studerich - did the ones you had have either or both vents plugged?

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            • #7
              From the service bulletin dated January 1957 after approx 1375 cars the base design was changed to include the drain tube to front of engine timing gear cover

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              • #8
                The drain tube and related parts. See this page and note on bottom when used
                Attached Files

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                • #9
                  I'm using the Chassis Parts Catalog for '55-'58 Studebakers and '57 - '58 Packard's. revised Jan '61. The notes are on page 75. Notes 15 to 19 refer to the drain and flapper valve. They are referenced to parts on page 81, which refer the drawing on page 73. You need those pages side by side to make sense of them! If you don't have that catalog, PM to me your Email address. I think I know how to send them.
                  I think the drain tube is a genuine improvement. One flapper valve should be sufficient. I guess the second one, in the base, was partly to provide a drain. Cross ventilation doesn't seem necessary. It's a potential air leak. Plugging it, and installing the drain tube are unobtrusive.
                  I have parts from a "57 Golden Hawk that have the drain tube and a flapper valve in the lid only. The base was never drilled for the valve.
                  Mike

                  Originally posted by 5brown1 View Post
                  Thank you all for responding. Al - your post made me remember that the previous owner had included some service bulletins which I found. SB #320 is the one you posted and it mentions that both vent holes (base and cover) were plugged and the drain installed to vent and drain the air chamber. Interestingly SB#325 indicates that later air chamber covers had no vent holes and a cure for hard starting of hot engines was to drill a 1" hole and install a flapper on the side of the cover.
                  Mike - where do you see the notes on the vent fitting and tube? I do not see them in the "super charger parts" section of my manual.

                  After reading the information I am inclined to plug both vent holes and install a drain in mine. What are your thoughts on this?
                  Anyone have more information on the size of the drain tube?

                  Comment


                  • #10
                    Thanks, I did find that but on a different page in my manual.

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                    • #11
                      Steve; I guess you got it to start and run! What was the problem? I think they thought a leaky carb would allow gas to accumulate in the box which could become a very effective bomb in the event of a backfire.

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                      • #12
                        Jeffry - I did get it running but I am not quite done tinkering at this time. Also had a carb problem going on which I just became aware of. There always seem to be two issues at the same time on this car which makes it difficult to pin down remedies. The weather is going to get pretty cold here so I won't be able to do much until we get mild weather.
                        I plan on going back to my original thread and detailing what I have done when I am sure it is running the way it should.

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