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When using twin H4s back in the day the various Cooper and S Inlet manifolds could be used and often mandatory in motorsport. Of course they were under size for the H4s being made for twin 1 1/4 and the Downton set up I have on a 661P inlet has been opened up a little to compensate but obviously not to 1 1/2” as you can’t. So my question is, other than fabricated tubular steel inlets what else was available in cast ali for a Mini that did fit H4s? I’ve an Oselli inlet of the right size made for HS4s, which looks like a later 573 S inlet, can that be redrilled for H4s? Any other aftermarket Ali inlets that will do the job? The inlet ports on my race head are big so I need to match up and I want to use H4s, I’ve got to assume the recast S inlets used by historic racers today are bigger than original Cooper/S ones and currently out of stock anyway.

TIA

C&T ?

Only had a CT one on HS4s but don’t they also fit H4? Any pics anyone? Just needs to look like a factory one. Nerus aswell maybe?

Alexander H4 kit.

All factory mini twin HS2 manifolds I have seen are machined out to suit the bigger H4 as standard.

The new recast twin su manifold is a horrible thing . Some people were welding up the factory inlets to alloy modifications but I believe the scrutineers have now stopped this .

Massive ports on a 1293 may not be ideal

As Simon has already said. Any Cooper or Cooper S inlet manifold can be opened up for H4's. It is really easy & takes about 30 mins with a decent air grinder. Another good one is the Alexander one.

I have done this literally dozens of times.

The size of the ports on the head require a full 1 1/2 inlet diameter and I don’t think you can get that modifying a 1 1/4 inlet without wrecking it or welding it up to add extra metal , always happy to learn though. So my question was which aftermarket cast ali inlets will take a pair of H4s. Thanks for the suggestions so far.

Mangoletsi did one for the Midget but I don’t know if that means it won’t clear a Mini bulkhead.

Yeah different angle of the dangle Tim. Think I might have cracked it with an Oselli one redrilled. I know you can tickle up a factory 1 1/4 inlet and match the head to that but I’m working back to front as I already have the head/engine so looking for a bigger option.

Pete wrote: ↑Fri Apr 01, 2022 11:26 am Yeah different angle of the dangle Tim. Think I might have cracked it with an Oselli one redrilled. I know you can tickle up a factory 1 1/4 inlet and match the head to that but I’m working back to front as I already have the head/engine so looking for a bigger option.

Had a look at their website and they still make it. Says needs wing modifications on a Midget, so defo won’t fit a Mini.

Their 1 1/4” one does look to have plenty of meat in it. http://www.mangoletsimanifolds.com/manifolds/mini.html

I'll have a look in the collection at the weekend. I am fairly sure I have a Mangolwtsi manifold for a Min. May even have others that can go out that big. TBH, I have never looked at them with that in mind.

I’ve got an Alexander manifold if you’re after one Pete.
Cheers. Mark

mk1 wrote: ↑Fri Apr 01, 2022 9:30 am As Simon has already said. Any Cooper or Cooper S inlet manifold can be opened up for H4's. It is really easy & takes about 30 mins with a decent air grinder. Another good one is the Alexander one.

I have done this literally dozens of times.

The original 1-25" twin carb assembly off my 67 S uses a 12A661 manifold, while it may be possible to open this up my 1-5" carbs would not fit as the flange on the 1-25's is vertical and those on the 1.5's are inclined at approx 45 degrees.

The pair of 1-5" carbs which I now use are fitted to a 12G2464 manifold - I have no idea of the origins of this as I bought up a job lot of mini spares which included this and a couple/pair of 1-5's which I sorted and assembled to fit. The only real problem I had was that the flanges on the manifold are square and quite bulky and I needed to file away part of the bottom edges to fit and create clearance onto the big bore manifold.

Have settled onto a needle/spring now and, short of a rolling road am well pleased.

Sorry, you will need to re-position the studs however, as mentioned the flanges on the 12G2464 are big and thick enough to allow this

H4 carbs have the same stud position as Hs2s

HS4 carbs are different

Thank you for the clarification

Thanks for all the feedback and generous offers. Once I took the HS4s off the Oselli inlet (well I think it’ Oselli, it’s not marked!) and put my glasses on I realised it’s also drilled for H4s as others were. It’s only a few mm bigger than an HS2 inlet but there’s much more meat on it to take it out to the size I need so hopefully we’re ok now.