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Single Amal Conversion

Discussion in 'Other Norton Motorcycles' started by Paul W., Sep 22, 2018.

  1. Paul W.

    Paul W.

    Joined:
    May 12, 2018
    What is a good baseline for setting up a single Amal monobloc on my ‘66 N15? Pilot, main, jet, and needle position? Also, would I need to change the cutaway?

    Thanks in advace.
     
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  2. Bodger

    Bodger VIP MEMBER

    Joined:
    May 9, 2017
    These are the factory specifications for the single Monobloc 376/294 on the early Atlas: choke 1.16"; floatchamber needle seating raised by 1/32" washer; shortened tickler fitted; main jet 400; needle jet 106; pilot jet 20; throttle valve (slide) 3 1/2; needle taper C; and needle position 4. I run this set up on an early Atlas and it is satisfactory although the pilot jet might be a bit rich. The early Atlas probably had lower compression than your motor. I don't think the choke is terribly important - I never use it. Otherwise these specs seem like a good starting point.
     
  3. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    My single carb Atlas had a split sleeve reducing the inlet dia in each inlet port, for slower running, could get 12-15 mph in top gear!
    ( pilot jet was 15)
     
  4. Bodger

    Bodger VIP MEMBER

    Joined:
    May 9, 2017
    Seems to me, and I may be wrong, but raising the float chamber needle with the spacer (washer) raises the fuel level in the float chamber above the standard level marked by the dot moulded into the float chamber cover. Presumably this was the result of some experimentation by the factory and was intended to compensate for the use of a smaller main jet than that used on the twin carb bikes.
     
  5. Bodger

    Bodger VIP MEMBER

    Joined:
    May 9, 2017
    Actually, to revise my original speculation about the float needle spacer, by memory, the twin amal set up with the single carb with the float chamber and the other chopped, also spec'd the spacer.
     
  6. Paul W.

    Paul W.

    Joined:
    May 12, 2018
    I should have mentioned I have an Amal 389/236. Do they setup the same as the 376?
     
  7. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    If you go here, you can find the specifications for all monobloks, and the bikes they were used on.

    http://porklips.org/~mason/moto/amal_specs.html

    If you study the charts, you will find the Amal 376/294 was used on single carb Atlas's, which I think would be appropriate for a single carb N15. Bodger, in reply #2 above has given you the setup for the 376/294.

    Slick
     
    Last edited: Sep 29, 2018
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