I am having trouble with my 1972 Mini Clubman purchased recently.

At one stage it had twin HS2s and extractors plus electronic distributor but at present is single carby, std manifold, points ignition and no vacuum advance.

The previous owner mentioned in a throw away line that the car had a “mild cam”.

On getting it home I tuned with a colourtune plug and timing light. Working off home made marks on the crankshaft pulley which seemed accurate, it idled best at about 20+ degrees BTDC and the colourtune plug showed blue at all revs up to 3000 rpm with the usual brief orange on acceleration.

The car will not idle at less than 1000rpm, it just chugs and stalls.

It does smell of petrol in the cab and hunts all over the place at what passes for idle. But for the bunsen blue I would guess it is running way too rich. There is a related problem of the T choke handle not wanting to raise the jet but I have stopped the choke by hand.
Then there is the camshaft. I would have thought even a full racing camshaft would idle better at 1000 rpm

Does anyone have any ideas on what might be wrong?

Could be nearly anything really
Bad fuel
Wrong needle or mixture set wrong
No oil or the wrong su damper oil
Worn out carb
Air leaks at the manifold or carb
Timing wrong
Spark plugs or leads no good
Bad compression or a blown head gasket

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Did you fit the single carb, manifold and std distributor?
If so, what did they come from?
What I am getting at is whether it ever ran well with previous set-up, or if your standard items created these symptoms.

I'm guessing an air leak at manifold or carb, which gives odd idling and especially if the throttle spindle is badly worn, it is impossible to get the idle back to stalling, even with the butterfly fully closed.

Thanks for the advice, I will double check everything tomorrow.

As it turns out it ran even worse until I discovered one of the plugs was bad and replaced them all. The carby looks new and so does the electronic distributor which I still have. Air leaks are a possibility but the the mixture is OK if the coloutune can be believed.

Does it have a lightweight flywheel? My flywheel is very light and a slow idle is not possible

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did I tell you that I won a trophy?

Unfortunately it cannot. The colortune is only testing the engine off-load. It is correct at idle because the assumption is that the right SU carb needle is being used. Once you drive it on the road, the SU piston will open right up under load (which it doesn't when being revved in the garage) and the mixture will be something else other than right if the needle is incorrect. Colortune is a great tool (I have two!) but assumes first that the carburetor construction parameters are correct. If you haven't touched the needle, then you will likely be fine if the previous owner chose well.

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SooperDooperMiniCooperExpertEngineering

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

May be too lean, try pulling the choke cable out slightly to see if it is better.

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Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)

Lack of fuel Lack of oxygen or lack of spark at the right time Three things to make the explosion

Try a new condensor
Use a Bosch GL103 from Repco
Plenty of dogy ones around