Hi all
It seems most wartime carbs fitted were 276C1 B type

Other carbs which appear to be the 276 014 R - this to my knowledge being the same carb - but issued by Amal as a replacement part in place of the C1 B type

Was looking at carbs I have here & found an Amal carb stamped 276 014 R type but still retaining the 4 holes at the bottom of the carb body associated with pre war type 76

So I have a 276 carb but with an earlier 76 type body
- anyone seen this before ?
Br
Jo’b

email (option): jonnyob1@googlemail.com

Maybe a new unstamped 76 body that someone outside of Amal has erroneously stamped. I'm sure John Parker will know. Ron

email (option): ronpier@talk21.com

Pre-1939 civilian M20s were fitted with the 76/014 complete carb, and a replacement body had the same number. This was upgraded in 1939 to the 276/014R (the 'R' indicating 'Revised' which incorporated the large single pilot air drilling and the casting gained the gusset under the inlet, to allow it to be bored).

Early in the war, Amal went over to a new system, with the carb complete with all settings and float chamber receiving a new code. In the case of the WM20, this was generally the 276C/1B (1B is the float chamber). Bare bodies continued to be supplied stamped 276/014R.

If the body you have with the side-drillings for pilot air as per the Type 76 also has the pilot airway bored in the inlet tract then I'd suspect that an owner has drilled the 276 body to allow use of a Type 76 jet block. Matchless went back to the Type 76 after the war. I suspect that if used without a filter, they actually work better than the 276.

If the body has the gusset under the inlet tract but it's not drilled through then it is probably an incorrectly stamped post-war replacement 76/014.

Must be a wrongly stamped body as bodies originally were type 6, then went to 76. The war office in 1939 wanted to be able to filter all air into the carb and changed from the 4 hole body type 76 to 276 which denoted the removal of the four holes in the body and jetblock. to complicate things AJS continued with th 4 hole type up to 1954, Norton Dominator 1949 to 1954 did the same and some racing Triumph in the early 1950's also had the 4 hole type 76 carb body. So in short 76 has the four holes, 276 does not.

I was waiting for that John:+1: Ron

email (option): ronpier@talk21.com

Hi if you knowlegeable carb guys can give an opinion on these images on my 276 carb, purchased in 2019 from Hitchcocks for my 1943 BSA WD M20.

1st set of images, running a Champion 86c, E10 Petrol, needle on 3rd groove, 170 main, 106 needle, air screw backed out i & 1/4 turns, plug image after a 20 mile non stop run at about 40mph.


Second set of images same as above but on NEEDLE GROOVE 4.


any advice appreciated.
JohnB

Hi John
I’ll try get the photos I have of this carb loaded here so you can perhaps make a call on what I have

Hoping my friend can use it on his June 39 K m20/21
Br
John

email (option): jonnyob1@googlemail.com

John has forwarded me some photos. It looks as if it has been boiled for half a century in a mixture of Castrol 'R' and Lynklife !

The body is clearly stamped 276/014R



It has the gusset under the inlet, and clearly the four radial drillings for use with a Type 76 jet block.



but, and this is probably the crux of the matter, it is bored via the inlet for use with the /R suffix jet block. To my mind, this can only be an owner-modified 276.



Incidentally, despite what Amal published after the war, the Norton WD16H was being fitted with a 276/011 carb as early as December 1936. This was with the Norton type jet block though, and not the /R type.

Thanks Rik
Once we get it apart here - we can check the block for type fitted -
Found out some new info again - which is always good

Br
Jo’b

email (option): jonnyob1@googlemail.com

Yes it is a 276 that has been modified by having the four holes drilled probably to suit the 4 hole jetblock that was laying in his shed/barn.

Agree with John Parker, Body Stamping looks original and it has the large air passage hole in the inlet track as a 276. The 4 holes are drilled for a type 6 jet block and as a later 276 block is fitted the body holes will be blocked off with the 276 jet block so the carb would function ok.