Missfire after hot start

[flying farmer]

I took the Stag powered estate to Telford to pick up the paint for the Stag today. I seem to have aquired a problem in that after a short stop, it will start ok but is a bit fluffy on idle and missfires badly on big throttle openings at low revs. It will however rev cleanly at small throttle openings. It feels like it is dropping onto four cylinders which makes me suspect a stromberg problem. The problem disappears after about a mile, and the only other time it has appeared was after going down a long hill on a trailing throttle.
I suspect that one carb may be flooding. Since I have very little experience of strombergs, does this seem likely?
Dashpots are full of oil and diaphragms were ok a short while ago
At first I thought it was an ignition problem as I cleaned all the connections in the ignition system and the problem went away, but it was an hour until I restarted it and of course it had gone cold by then
Neil

[martin]

Hi, I agree Neil, it sounds like one needle valve has given up the ghost and is letting that carb over-fuel. Easy cheap fix but a nuisance all the same. Martin.

[Colonel Mustard]

Just a thought...but if it's not idling very well, try unscrewing a dashpot (while the engine is running). Then lift the damper about 1mm and see what happens. If the engine speed increases immediately then the mixture setting is too rich. If the engine speed decreases or stalls, the mixture is too weak. If the engine speed increases slightly and then returns to normal, the mixture is correct. Screw the dashpot back in and repeat for the other carb (the engine might stall when you push the damper back in due to getting too rich, but will start again okay).

I know this is basic and crude, but might tell you if you're dealing with a carb problem or not, and if so which one.

Chris

[Colonel Mustard]

Another thought has spung to mind. What type of petrol are you using? A lot of standard unleaded fuel now has Ethanol blended into it at 5% mixture. This is renowned for causing (amongst other things) vapour lock and poor running after the fuel has been heat soaked. If you're using super unleaded there is less chance that ethanol is in the fuel but in any case the fuel pumps don't tell you whether they dispence ethanol fuel or not...coz they don't need to

See this list below. I got the information from the fuel suppliers directly last Month...

BP…Ethanol is added at 5% to unleaded petrol at all sites across the UK. BP Ultimate (super unleaded petrol) does not have Ethanol added…except in the South West of England.

Esso…Ethanol is added at 5% to unleaded petrol at most sites in the UK. Esso Super Unleaded petrol does not contain Ethanol…except in the South West of England (Devon & Cornwall)

Shell…Shell has repeatedly refused to answer the question. It is therefore an assumption only, that all Shell petrol should be considered to contain 5% Ethanol.

Texaco…Ethanol is added at 5% to unleaded petrol. Texaco Super Unleaded petrol does not contain Ethanol.

Total…Ethanol is not added to Total fuel (including standard unleaded petrol). Except in the North West and South East of England.

Chris