The typo and all other marking on the carb are just not there , I’ll post more pics of the carb soon.
Remove a brass cover and take a pic of the progression holes.
That's where a lot of the differences reside.
Then the crossflow has no mechanical pump yet . It even looks like the lobe on the cam is not there. I’m assuming it had a plunger type regulator and I just can’t see the lift. I’ll put a dial indicator on it soon. 🥱
My 844 (EFI) engine has no provision for a mechanical pump on the head and no lobe on the cam, either.
Were the 843 Turbo engines similar?
Some Weber OEM's show two "Typo" numbers in sequence. I think the R12 Gordini is such a case. All it means in this instance was for the factory to be able to differentiate between front and rear carb in terms of some fittings. The jetting etc. is the same.
My original tame R16-TS engine ran 2 x Weber 40DCOE's which came originally from an Elan. It ran great and with rather impressive fuel economy as well.
Later, I extensively drove a mates more powerful 1647 crossflow engine with 2 x Weber 45DCOE's. It also ran great but the economy wasn't as good and it had a bit of a stumble going onto the main jets. I expect both aspects could have been improved with a little tuning diligence.
I still reckon the sweet spot for most of us is 40's and have a set of the older Dellorto 40 DHLA's just to try something different.