Model 18 ohv

Its a 276 Ian IE clicky clicky:

http://amalcarb.co.uk/pre-monobloc/76-276-series.html

or

http://amalcarb.co.uk/generic-type-276.html

Good luck.

Rgds Steve

Had a look though a couple of books and no mention of a Model 18 special that I could find. The Roy Bacon book on singles lists the carburetors for models grouped 1946-1954 not 1949-1954 as on the Amal list. The Model 18 carburetor specs listed in the book are the same as what is on Amal's list for the Model 18 special, so there doesn't appear to be anything "special" about the carburetor. You could always ask the clubs keeper of the serial numbers if there is any record that indicates there was one. Other than that, I have no clue and I'm no expert.

You could go mad trying to extract specifications from Amal's parts listings. The VMCC though hold all the carb build cards, by make and model so could maybe shed some light.

Amal changed their numbering system during the war years so each carb body and each float chamber have their own part number, and each carb and chamber supplied as a complete unit also had a different body number but including the float chamber suffix.

The 1946 - '54 listing for ES2 and 18 includes a 'V' suffix on the body which I believe refers to the 'Veloce type' throttle stop screw (the cold start device).

Apart from that, the body is the same so the difference probably lies with the float chamber.

The 1BE float chamber seems to differ from the 1DW in that it had a single banjo and the DW a double....

I can't help wondering if the 'Special' actually referred to a special order with Amal, the details of which accidentally found their way into the main Amal fitments listing.

Having searched through the cards at the VMCC (only for WD models, sorry ) I can certainly imagine how a clerk in the technical office could have taken a mis-filed one-off build card headed - Norton, Model 18, 'special' - and added the details to the fitments publication. The cards include a lot of pre-production and development builds...at that point of course they didn't know whether the specification would be adopted by the motorcycle manufacturer.

The card below relates to a WD Big 4 but gives an idea of how Amal were working at the time.