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Thread: 72 mfi stacks

  1. #1

    72 mfi stacks

    I'm planning on putting the mfi back on my car. Are these the correct stacks? 901 110 309 OR
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  2. #2
    Senior Member
    Join Date
    Oct 2002
    Suffolk, VA
    The 1972 stacks are plastic, rather than magnesium as on the earlier cars. I can't tell from the photo what yours are. Also, the throttle size is larger on the S vs the E and T.
    1970 911S Coupe (Burgundrot) (sold)
    1967 911 Coupe (Light Ivory) (mostly gone)
    1966 911 Coupe (Sand Beige) (sold)
    Van Diemen RF99 Formula Continental
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    Other Early 911/912/914

  3. #3
    Thats what I thought. The top pieces are plastic as you can see I have a few chips in them. The main part of the stack is metal.

    I guess I'll keep an eye out for the correct ones. Does anyone have a part #.

    Thanks for your help.

  4. #4
    Also is there a differece with the throttle bodies between the T, E, and S?

    I do know I have a S pump.

    Thanks again.

  5. #5
    Senior Member
    Join Date
    Jan 2003
    NW Indiana

    You can measure the diameter of the Throttle body openings (side against the heads and the stacks) and also measure the bottom and top opening of the stacks. Then compare them to this chart from a very helpful Pelican post.

    Throttle body and stack measurements

    Should give you a better idea what you have.

    R Gruppe #299

  6. #6
    FWIW, both plastic stack on my '72 911S have a number cast in them.. 911.110.312.1R Dunno for sure if this is a part or a casting number.
    Paul D. Early S Registry #8 - Cyclops Minister of West Coast Affairs
    "Now, to put a water-cooled engine in the rear and to have the radiator in the front, that's not very intelligent." -Ferry Porsche (PANO, Oct. 1973)

  7. #7
    Well my stacks measure 38mm on the bottom and 46mm on the top , so that looks like a 69S stack. My throttle bodies measure 36mm on the bottom and 38mm on top, so they are S specs also.

    The throttle bodies seem tight and there is no light shining through when held up to the light.

    I think I'm going to wait till next winter to tackle installing the MFI. I want to drive the car this summer and can wait for this project.

    Thanks for the help. Now I know what I have. I still need some small stuff but I'll just keep my eye out for parts.

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