Hi all,

Have a set of twin H4 SU carbs for the cooper s, it's currently bolted to a speed-o-motive 850 1100 (?) manifold. Anyone heard of these? What manifolds do you recommend? They have the same stud pattern as the 1 1/4" SU's. How hard is it to put a rebuild kit through them? SU midel just quoted $600 to get them done! I'm tempted to have a crack!!

Its not difficult to put a kit through, unless the spindles are worn, then it takes a little extra work.

Wriggle the butterfly shafts and see how much movement you get. If there is a lot of movement, then air will sneak through the gaps when idling and make tuning almost impossible.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Thanks for the reply Mick, doesn't seem to be too much movement so I think I should be ok! There's not much info about the manifold on the net. Here's a pic of it:

There were no shortage of aftermarket manifolds back in the day, but I couldn't tell you any more about the manifold. Maybe someone else knows?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Check that the diameter of the manifold tubes mate with the carburettor diameter, as few early manifolds were made for 1 1/2" carburettors. The cost of rebuilding a set of SU carburettors can be more than you first expected, but is usually worth the effort as it is fairly straightforward, and parts are available. Quotes for overhauls of H4s are often "high" because they are highly valuable in "historic" racing/rallying/restoration categories and to convince you to exchange yours for alternatives.

When I did mine I found the most cost effective way was to totally strip the carbs yourself right down to just the body,and find a carb shop that will just do the tricky bit for you ie rebushing the spindle and butterfly etc if needed.

I'm sure if you ask you should get some recommendations. SU Midel certainly do an amazing job and plus the carbs come back in better than new "super-bling"polished condition so you pay for that really.

Try and find an old school Carbie place to do it. I was going to order the other parts myself but I found they charged less anyway so i just got them to get me the parts i needed. Most places would get the bits from Midel anyway.

Reassembling and setting up the carbs is not that difficult, just keep careful note of where everything goes. There's plenty of guides online or just ask here if you are not sure.


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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)