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Supercharger impeller clearances

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  • Engine: Supercharger impeller clearances

    I'm resealing a VS-57 and in the 1957 supplement shop manual they call for a clearance of .046 to .051 between the impeller and diffuser and on the SN 60 in the 1964 shop manual they call for .012 + or - . 004 . I'm sorry i didn't check the clearance the impeller before I disassembled it but I know it was alot less than .046. Anyway at .046 the impeller hits the scroll cover ? I wonder if there was a service letter put out on this ? Also this is a 2 owner Golden Hawk and in the 30 plus years the current owner has had it the supercharger has never been off the car and he got it with 16,000 miles But when I dismantled the supercharger there was no gasket between the diffuser and scroll cover ? Ed

  • #2
    Per Phil Harris. Put 3 pieces of masking tape on the impeller. Tape should just touch scroll cover. I use this system and it works.


    • #3
      On VS 57s I shim until it just scrapes, then install the gasket on the scroll cover. The closer the clearance the more boost.
      Of course you never want it to rub at any time during operation.
      Bez Auto Alchemy

      "Don't believe every internet quote" Abe Lincoln