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Technical McCulloch M-40 supercharger

Discussion in 'Traditional Hot Rods' started by AULIZ, Nov 21, 2014.

  1. AULIZ
    Joined: Oct 28, 2005
    Posts: 1,287


    I bought 2weeks ago McCulloch supercharger to Flathead Ford.
    Its M-40 model.

    Can You tell me what year is it?
    What is value, if good condition?


    NB. There is problem with drive gear, but I know company where they have done me italmeccanica drive gears,... so I can solve this problem.

    Attached Files:

    joacim bergman likes this.
  2. bigorangetruck
    Joined: Oct 23, 2012
    Posts: 54

    from TX

    Could you list the model and serial numbers? I believe there is a date code in one of them.
    As for price, I would say $1500+ easy.
  3. alchemy
    Joined: Sep 27, 2002
    Posts: 17,452


    Value will be effected a bit by the crack on the carb mount.
  4. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,608

    Rusty O'Toole

    Have you seen this website? The best source I know for McCulloch supercharger information.

    From what I know of their model numbering system, an M40 was probably made in 1940 to fit a Mercury V8.

  5. and the buggered drive gears
  6. AULIZ
    Joined: Oct 28, 2005
    Posts: 1,287


    Supercharger is on the way to Finland. Need to open it when arrive.
    Hope that housing and rotor are cood condition.
    Bearings are free for me (I sell bearings like my dayjob). I have to pay little new gears,
    but I know a company which helped me with Italmeccanica 4000 gears and
    they have 80 years experience gearboxes, gears. They can make new set, harder teeth etc.

    Serial nr is 2604
    Model M 40

    I know that these old superchargers not give more horsepower, but it looks so good
    and if I think my new project 1940 panel delivery, there is so much free space.

    Last edited: Nov 22, 2014
  7. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,608

    Rusty O'Toole

    Actually they do give more horsepower, McCulloch advertised 30 - 40% more rear wheel HP.

    The old flatheads were tuned for smooth low speed performance but ran out of breath at higher speeds. The centrifugal blower does little or nothing at low speeds, but boosts power at medium to high speeds.

    Flathead engines are also limited in their compression ratio to about 8:1 or less. You can't make the combustion chamber smaller without cutting off the breathing.

    Low compression works well for supercharging. Your blower will give a maximum boost of 4 - 5 PSI or about 1/3 atmosphere. This has the effect of increasing your compression from 7:1 to 9.3:1. Perfect for today's higher octane gasoline.

    They worked particularly well at high altitudes, where the blower made up for the thin air.
  8. AULIZ
    Joined: Oct 28, 2005
    Posts: 1,287


    interesting info.

    I have 8BA (50) engine in my 1940 panel delivery. Original comp.ratio, original cam.
    I have used Isky 3/8 cam on stock but original in engine. Maybe I bolt on that blower set on
    that engine.

  9. nrgwizard
    Joined: Aug 18, 2006
    Posts: 1,458

    from Minn. uSA

    Should work well w/that cam. Also, when you get into the blower, you'll find, unless it's been modified already, that the clearances around, above & below the compressor wheel are horribly, uhm, large. Thus, both heating the air & limiting boost, at the same time.If you want better performance, you'll have to do some careful measuring, machining, & maybe milling or grinding; to close up the gaps. Somewhat more in line w/how turbos compressors' clearances are finished. & the better bearings will help. Which will of course help to atomize the air/fuel even better. Will never get a lot of boost, but I'd guess at least 50% more than factory-stock. Which would/will be very noticeable. The impeller design is, iirc, straight vaned, & will only throw so much air, & the gearing is probably the limiting factor in how fast the s.c can be turned. You've got a neat/nice piece of equipment there.

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