Inlet manifolds - twin H4s

[Pete]

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

[almondgreen]

C&T ?

[Pete]

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?

[NZmember]

Alexander H4 kit.

[251 ENG]

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

[mk1]

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.

[Pete]

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.

[Oneball]

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

[Pete]

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.

[Oneball]

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

[mk1]

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.

[rolesyboy]

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

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.

[Allen Brzeczek]

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.

[Allen Brzeczek]

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

[almondgreen]

H4 carbs have the same stud position as Hs2s

HS4 carbs are different

[Allen Brzeczek]

Thank you for the clarification

[Pete]

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.