your brass bush was indeed the Idle fuel jet , you need a magnifying glass to see if there is anything in it , and try to look right through the centre at daylight ..

Thank you, I nearly lost it when it fell off!!

Back in the days when I used to worry about having my 340 nicked I wired a hidden switch to this solenoid. The car would start, run for a few hundred yards then stall, and stall again. Caught me out a few times too.

Do an LPG conversion. All the stuff about blocked jets stops being an issue. Lovely engine bay pics, all those lovely parts to salivate over...

It sounds to me like an air leak at idle. Usual symptoms are fine running at speed when the quantity of extra air won’t make a difference but at idle it significantly weakens the mix. A place worth checking is the brake servo. It draws its vacuum from the manifold and any leaks in the diaphragm will dilute the mixture. A simple test is to block off the pipe and see if matters improve.

After I've finished a cuppa I going out in Volvosaurus, 5 miles there, some work for a couple of hours, then 5 miles back. I report back later today. Not paid work I'm afraid!

My nephew is currently installing a Tesla motor in an original mini. Complete rust proof of body shell and the rest and a massive bank of batteries in the rear seat. Very original.

Just to clarify, are you using the words "Tesla motor" as a generic term for an electric motor or is it a genuine Tesla motor?

If it's the latter that thing will be seriously mad, the Tesla itself is mad enough in terms of performance but in a Mini that only weighs a fraction of a Tesla that will be scarily quick!

I did quite a few LPG conversions on 300's in the 80's Very successful , I still have the parts in the attic with the torpedo tank , as they were removed when it became uneconomic in the 90's , it would be transformed these days with electronic control and a low pressure turbocharger ...

This is very interesting, would like to know how this progresses. Some time ago I did a post here suggesting electric for the 340. I think it would make a great conversion. I have a Riley Elf Mini too, more space in the boot for batteries!

The 300 series would lend itself nicely to an electric conversion because of the rear transaxle. Either the space the transaxle takes up could be used to house the motor directly driving the rear wheels (perhaps through an integral gearbox) and the space and weight taken by the engine could be taken by batteries instead or alternatively the motor in the engine bay (with some batteries to balance the weight) with the majority of the batteries in the rear in the space the transaxle used with a different replacement rear axle.

On another forum, someone started a thread about converting classics and asking for suggestions of suitable classics for EV conversion. My suggestion was the NSU Ro80. Assuming an intact example could be found that hadn't been converted to Mazda RX-7 power and that the original ****el engine was dead, fitting a motor in place would be a good conversion as the rotary engines had a noise not unlike an electric motor working hard.

The possibilities are endless but i have a feeling that EVs will only be a "BandAid" on the environmental problems and a better, cleaner fuel will be found enabling the continued use of IC engines with little or no modification and much cleaner emissions.
If there was an easy way to create Browns Gas aka HHO aka Heavy Hydrogen aka HOH and other simlar names, that would be near perfect but at present it takes more energy to split the water atoms into hydrogen and oxygen than would be derived from burning it.

Meanwhile LPG is as near as we can get to that kind of cleanliness and only 50-60p/L. As you have a carb engine, it is much easier to fit than an injection engine and would be a good move IMHO.