The BSA Twin Carb Mystery
What The Public Got
Did BSA ever do more than keep the twin carb option open? I believe they did, but if you think I've been building a case based mostly on emails from people I'd never met in the the US and Canada, then consider the following.
Authorised Accessories in the USA
I have a copy of an American dealers sales brochure showing a range of performance parts for pre- unit BSA twins, approved by BSA and bearing BSA part numbers.
The A10 parts are the same as the ones described by people in the US and Canada so they were probably supplied as after market tune-up accessories, in the same way as Dresda and Rickman in the UK produced parts to make Triumphs and Nortons go faster.
Brochures produced in different years list
parts and prices as follows;-
A7 twin carb head
A10 twin carb head
Manifolds for above
Two carb kit including the head, manifold, twin throttle & cables, nuts, washers, studs and two monoblocs, one with cut-off float chamber
This raises a couple of questions. First, did the approved status mean that BSA would create a part number for any new equipment manufactured by/for the dealer who was not original issue for that model of bike? Second, the 1954-56 A7 alloy head is listed here as a twin-carb part. Since it at least is listed in the 'official' BSA parts lists as a single-carb head, why would BSA approve what appears to be fraudulent advertising?
To find out, read What were BSA Up To? ...