Thanks, I have a similar book on the Stromberg carb, which I bought second-hand many years ago, and which also has needle profile charts at the back, and I've just updated it with further needle profile charts from Burlen Fuel Systems, who now own the Zenith, Stromberg and Solex 'brand', but, as you say, no reference to Land Rover part numbers therein, or on their website.
For anyone who has a slightly later Land Rover V8 engine (maybe like me fitted to their Stage 1) and is interested, there are four different metering needles shown in the 110 (up to Aug 86) Parts Catalogue, and I've identified the Zenith number for a couple of them:
I'm now pretty sure AEU3077 ('Engines 15G, 19G & 21G') is Zenith needle B1FK, and AEU1851 (Engines 17G & 22G) is B1FH. I don't know but my educated guess is that the other two, AEU3078 (for Engine 14G) and AEU2462 (20G) are B1FQ and B1FV respectively, but I'm not sure of that. Knowing is the difference between taking Land Rover's (and the parts supplier's) word for it, and paying as much as about £50 for a 'Genuine' needle, and buying a needle you know the exact profile of for about £15 from Burlen.
You can choose a needle using Burlen's website but they use a rather vague guide based on year 'onwards' (they list 6 different needles for the V8 for the years of production of the Stage 1, not including the Range Rover, where my Series 3 Parts Book only lists one!) or carb spec number, if you know it (and which assumes you still have the 'right' spec carb fitted to your engine - or, if you're happy, you can just replace like with like (assuming you have one of course) I did both the latter a couple of years ago when my carbs were rebuilt, replacing the B1FQ needles with new the same, in accordance with the spec number on little aluminium tabs still attached to the carbs, never giving any thought to my engine number - the Burlen site doesn't mention engine numbers, or Land Rover part numbers. I'm happy with the performance of the carbs and the engine except that I'm right on the edge of the idle adjustment for the MOT and I wondered if a slightly wider (at the relevant end) needle might be an answer, which needle B1FV, which the Burlen site says was fitted from 1985 on, happens to be.
I asked Burlen if they could tell me what needle Land Rover part number AEU3078 (for my 14G engine) was, hoping they would say B1FV, but they just replied "AEU3078 can be replaced by B1FQ", which doesn't answer the question, and is what I already have. I am beginning to think AEU3078 is B1FQ. I've asked a couple of suppliers with whom I've spent
lots of money in the past who say they have stock of AEU3078 if they'd kindly peer at it and let me know what the minute nearly invisible number engraved on the needle is, but I'm still waiting for a reply (!) ... and not hopeful!
I'm slightly less willing to experiment with an 'incorrect' needle, especially now I've just learnt from James Taylor's article posted on Rocky80inch's 'New owner of RHP 175R' thread that BMIHT had their own workshops at Studley Castle, which is where the present engine would have been fitted some time in the 80s, when it was their own vehicle, and they probably knew what they were doing.
If anyone at all has been interested enough to read all this, I shall now sit back and wait to be told I don't know what I am talking about. I note the question has been asked before on here - do the carb needles need changing if I remove the restrictors? - and that no one has ever replied - what I've said about identifying needles by a number that enables their exact profile to be ascertained may have some bearing on that question, but I haven't addressed the question directly, because I don't believe this engine was ever fitted with them in the first place, and my carb spec is also later than the year of the vehicle's production.