Stepdown fuel pump gasket thickness

GrimGreaser
GrimGreaser Senior Contributor
edited November -1 in HUDSON
What is the thickness supposed to be for the fuel pump gasket? I've seen talk about making sure to use the thick gasket when dealing with the fuel pump, can't find a thickness measurement. Well, my '52 (AC double-action pump) had a thin gasket when I got it. I would like to make my own, and need a thickness dimension. Or, do I use the thin gasket? Operation seems fine, that I can tell.

Thanks!

Comments

  • Unknown
    Unknown
    When the old one came off, there should have been a gasket stack, that was about 3/8 to 1/2 thick. You want to use that. It is like a spacer. I would use some RTV on both the new gasket and the stack, never had a problem. I am using the 83 AMc pacer fuel pump, which is a direct bolt on, but got to route the line, a tight bend.
  • [Deleted User]
    [Deleted User]
    The gasket stack (spacer)is probably more of a heat issolation effort than
    anything. The theory was vapor-loc seemed to start in the fuel pump on Hudson's.
    As you said the pump will fit with a thin gasket. However I have used that AMC one mentioned without a thick gasket and got a knock.
    Roger
  • GrimGreaser
    GrimGreaser Senior Contributor
    Yeah, vapor lock is an issue with the pump. I plan on plumbing a bypass when I get to dealing with the gas tank.

    And some have said running without the spacer will destroy the pump. Mine didn't have one when I got it, so I want to be sure I have things right.
  • Jim Kilday
    Jim Kilday Expert Adviser
    What is the proper thickness of the gasket stack for a 1946 8-cylinder?
  • schillaz
    schillaz Expert Adviser
    I maybe wrong here, but i believe the spacer does more than just stop heat transfer, Its for the lever of the fuel pump to ride on the cam in the correct position to get the correct lift on the fuel pump lever for the diaphragm to pump.


    hope that helps
  • [Deleted User]
    [Deleted User]
    It serves bolth - look back a few posts. You stepped into the middle here,
    Roger
  • schillaz
    schillaz Expert Adviser
    i was just trying to clarify why the spacer is needed and explain if its not used a guy would damage his fuel pump.

    no harm intended just adding to the post for future references.
  • Clutchguy
    Clutchguy Senior Contributor
    edited October 2010
    Read the shop manual. I believe it calls the thickness 5/16th's and some other procedure to go with it. I just removed a broken fuel pump from a '39cc8. It had no spacer ,just a gasket that was about .015 thick with alot of silicone.
  • [Deleted User]
    [Deleted User]
    The gasket pack is 3/16 to 1/4 inch. It's used to make the pump arm flat spot ride in the middle against the cam. With no gasket pack, just check where the cam is riding, up on the arm and not on the flat spot. With to thick a pack it will ride on the end of the flat spot and do damage to the cam. AMC pumps must use either thickness I stated above. No gasket pack, broken arm, to thick, not enough pressure. You want 4 to 4 1/2 pounds of fuel pressure. Walt.
  • GrimGreaser
    GrimGreaser Senior Contributor
    Thanks Walt, exactly what I needed. With all the different thicknesses thrown around I wasn't sure what to do. Then you slap me in the face with the obvious answer... "Look where the wear is!" Eh, not the first time, definetly not the last, that the simple answer slips through the murky, cluttered mess of my brain. :)
  • Jim Kilday
    Jim Kilday Expert Adviser
    Walt--is the measurement the same for a pre-stepdown 8-cylinder?
  • [Deleted User]
    [Deleted User]
    I make and sell the correct gasket pack as it must be tightened and will be all you need. If you have my tech tip books, go to volume one (1), page 34 and it has the complete story about pumps on 42 to 47. Yes, they require a spacer and the bakelite sleeves. I have this item also. Walt.
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