Roger wrote:

Some Lotus Elans (S4 with a hump in the bonnet) and +2s used a pair of
Zenith-Stromberg carbs.

According to the workshop manual these were 175 CD 2S or 2SE. The S is
the non-emisson and the SE Exhaust Emission. No idea if the lack of SE
in the query is significant.

Just an omission, though I suspect they're SE. The casting doesn't say
either and the tabs are illegible.
Thanks for the pointer. Lotus stuff goes for silly money on eBay so I'll
do a dual listing under Lotus and Triumph...