Hot Engine dies on idling

Try it and see if it makes any difference

Older versions of Stromberg/SU carbs had an easy main mixture adjustment at the bottom of the pot,with a change in regulations this was sealed on later models. This type has a bottom like a mini oil sump.There is a blank cap on the bottom that can be removed to access the adjustment screw,this then needs a special tool to adjust but I do not remember what it was like.

These types of carb's need oil in the dashpot to work correctly. What it does is slow the opening of the needle jet as you accelerate to prevent a rich cut.

+1 on it needs oil to work. Otherwise it drops too quick & shuts off.

X1 on topping up the oil. My old MGB GT SU carb had to be topped very regularly but if done so it ran fine.

May be miles out with this suggestion but my 2.25 petrol S3 wouldn't run recently and it was the coil overheating.

Al.

tottot said:

Older versions of Stromberg/SU carbs had an easy main mixture adjustment at the bottom of the pot,with a change in regulations this was sealed on later models. This type has a bottom like a mini oil sump.There is a blank cap on the bottom that can be removed to access the adjustment screw,this then needs a special tool to adjust but I do not remember what it was like.

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@kyamon , to do the mixture adjustment in the later type Stromberg CD, it is done by screwing the needle, located in the dashpot piston, up or down as required, to carry out this adjustment a special tool is required. The tool (from memory), is like a long allen key within an outer tube type spanner that holds the dashpot piston whilst the allen key bit engages the needle which has a thread to screw it up or down. The tool is inserted through the top of the dashpot damper rod aperture, with the damper rod removed.
The amount of oil required for the damper is only a few drops, don't fill it up to the top, this will interfere with the correct operation of the mixture vs throttle position. @Flat 6 also may have a good point, your problem could very well be ignition related, check the ignition contactpoints, coil, condenser, ignition timing and all the auto/vacuum advance sytem for function/integrity.

Hicap phill said:

+1 on it needs oil to work. Otherwise it drops too quick & shuts off.

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It is to control the rise rate of the piston rather than the drop rate, when the throttle butterfly is opened, vacuum lifts the piston, without the damper the effect of the vacuum lifts the piston at an uncontrolled rate against the dashpot spring, bearing in mind the mixture is controlled by the relationship of a tapered metering needle inside the fixed jet the engine requires that the fuel quantity supplied be commensurate with the butterfly valve opening.
On the other side of the coin, when you take your foot off the throttle pedal and close the butterfly valve, the vacuum effect on the piston stops and the dashpot spring pushes the piston/needle assembly downward you want the fuel flow from the needle and jet to drop off instantaneously to prevent pollution and engine run on, thus the damper works in one direction only.

Dashpot oil tube needs to be filled as there is no other control of amount of oil. Damper needs to be immersed in oil for its complete travel to work effectively.
Damper works in both directions. Against vacuum in one and against spring in other.