Yes, I'm interested. I'll have to update the carb article since you've pointed out something is not quite correct with the article.

I know this topic is a bit old, But I've been doing some research latley for my MGB and came across this post and thought I might share some Ideas. I have a later model 'B' with the Water choked Zenith Stromberg 175 carb. Earlier versions of this car had dual SU HF4's or HIF4's. For those not familiar with the ZS, it was switched for the SU to comply with strickter emmisions regulations around 1975. This led to a decrease in BHP and adjustability over the SU HS/HIF4's. So, I got a set of HS4's and a manifold and starting reaserching tuning of the dual SU's and now I'm here writing this.... so anyway... A little about the SU's (and what I've gathered about the Hitachi equiv.). The letter designations in all of these carbs basicly tell you the size of the carb. IE Hitachi HJG46W is the basic equiv. of the SU HS6 or the ZS 175 or a 1.75" carb. The Hitachi xxx38x (sorry didn't write down the exact model of this carb) = SU HS4 = ZS 150 = 1.5" Carb. and then the SU HS2 = 1.25" carb. The Z cars used the equiv of the SU HS6's in two styles. The round top (a copy of the HS6 as far as I can tell) and the Flat top (Different from the round top and suposedly less reliable, and tune differently than the SUs).

Now, I'll admit that I'm not that familiar Datsun/Nisson engines, but, I think that info on British engines will translate well. A specific size engine will have an optimul (or close to it ) carb selected for THAT size engine. Modifications to the engine will require rethinking the carb choice, but I will touch on that in a bit. So, Given these 3 carb sizes (there are more) what are the given set ups for engine sizes?

Duals first as these have a bit more WOW factor:

997cc to about 1300cc (Minis and Spitfires) use dual HS2's (1.25")
From about 1300 - 1800cc (MGB, Austin 1800) use dual HS4's (1.50")
~2.0 and up use Dual HS6's (triple HS4 or HS6's for some 6 cylanders) Z cars, some Volvos, GT6's, etc.

As for single carbs you basicly see a 1 size higher carb.:

997-1300 - HS4 (ZS 150)
1300-1800 - HS6 (ZS 175)
> 1800, I'm not really sure HS8's perhaps?

I think that it might have been said here already, but using too much carb will just bog down your engine, especially in the case of dual carbs. That is of course unless you have modified your engine. Modifications would include but are not limited to: P&P head, Headers, Hot cam, Over bored pistons, etc. Basically without modifications the engine will not have enough vacuum to properly operate the carbs. It might run, but it will be very difficult to tune it properly. Now for a single carb, you could possibly go to a higer than starndard carb and be able to tune more easily, But I don't see the point if the engine doesn't have the Mods to really benifit from it.

As an ending note, the SU carbs are highly tunable. there are some 300 odd needles to choose from, different springs, as well as other tricks. SU's abound, just check the e-bay listings for the MGB in particular.

As for the original Post, a Single Z carb could work on a 1.4L. A single SU HS4 or HIF4 would probably also work well as well as a ZS 150 or 175. If the engine was stock, I would probably start off with a 1.5" inch carb. Headers and a little head work could see the benifit of a 1.75" carb. As for duals I'd look into fitting a dual HS2 setup from a spitfire , or a mini.

You're on your own as for manifolds. Check Lynx, Cannon, etc. for aftermaket conversion manifolds, who know's you could get luckey.

Hope this is usefull to someone =)

-D.