Ian and others....OK   I am leaning towards using the HS4 carbs now.  Less likely to leak as well.  I am reaming the bushings on my HS4 carbs and installing new throttle shafts.  The HS4 carbs are actually about 3/4 an inch shorter than the H4 carbs.  Should leave more room.  I have lots of HS4 carbs from Austin Healeys and the parts are easier to get.

Dogscarf

Like CT suggests, H4s from an inline engine are different from those fitted to a Mini.  Basically they mount at a different angle and need to modified for use on a Mini.  

While they are in no way "original" for a normal Mini they were used on the Works Minis - because of the regulations.  While carbs were free under the regulations the original manifold had to be used - and the H4 bolted straight onto the Mini twin carb manifold.

IMHO your best bet is to sell the H4s to someone looking at making their modified Min more "period" and using the money to refurb your HS4s.... perhaps with some $$ left over - depending on how much the purchaser thinks they will have to spend to Minify the inline carbs.

BMC Special Tuning sold HS4s on a Mini specific manifold to those not so closely controlled by International regs ..

Cheers, Ian

The H4 s I think come from a old MGA and setting up the choke linkage looks like a nightmare. I think the old school approach was to use only one carbs choke for starting. I have buckets full of HS4 s mostly from single carb minis and MGBs. I'm currently working a set of HIF 38s from a later MGB. 

While the H4 s have vertical mounting and fit the original intake with a little opening up there are intakes that have the angled mounting bolts. I have found when fitting the C-AEG 489 to a ported head with the comp.gasket I have to weld the lower edge of the head side and file it down to cover the port. First one I installed had a vacuum leak, while small it made tuning impossible. 

I'm also working on my collection of HIF 38s. The MGB ones are set up for twins ad have angled two bolt mount. The mini ones have four bolt mount linkage and fuel line for one.

I'd suggest you work with the HS 4s everything about them will be easier. Linkage is the same as your HS 2s needles and other parts are easy to locate. I'd like to see some pictures of your H4 s as there are several and getting ones with the correct angle for a mini is the trick. None of this may be correct but I tried. Steve (CTR) 

Fellow Minioids,  I have some extra carbs laying around.  I have some 1.5 inch HS4 SU carbs off of Austin Healeys that I could re-purpose for my two Mini 1275 S projects.  I also have one set of H4 SU 1.5 inch carbs where the choke is an archaic mechanism of levers with a ton of play in them.  The number on them is AUC-6020.  I understand that the H4 carbs are original but would the HS4 be a better carb choice and more efficient?

Dogscarf
1967 Morris Cooper S Aussie
1968 Morris Cooper S