thats good advice james
start with underpants, then the cleft
after that up to you

Daft question, but are you sure you're actually looking at the main jet? I think the only single choke carb I've looked at very closely was probably yours last year, so I could be making all this up. However, I would guess there's a brass 'spout' which extends into the middle of the carb barrel? That's the outlet from the accelerator pump. Even when the engine's not running, you should get a short spurt of petrol from this every time you open the throttle.

I would expect the main jet to be nestled in the bottom of the float bowl. I can't find a picture of it on its own, but I think it's probably the one in the bottom right hand corner of the photo here http://www.ecas2cvparts.co.uk/carb-gasket-1970s-single-choke-solex-34pics-p-833.html

Of course, it could be electrical, as mentioned. We had similar symptoms with the Charleston over New Year, which had me convinced we were suffering from either blocked jets, or water in the fuel. It turned out to be a dying coil...

hi luke i couldn,t put into words what u just said but i reckon ur spot on

as ive mentioned time and time again the acellerator pump maybye fucked
or the sqirty pipe blocked
thats it, no more posts on this subject fineto

I perhaps should have made clearer that I don't think the accelerator pump is at fault! If anything is blocked, I suspect it will be the main jet. I just wanted to make sure Sam wasn't getting confused between the two, as his description sounded a bit like he might have been.

The accelerator pump delivers a small 'shot' of fuel as the throttle is opened, to allow for the momentary lean mixture being delivered while the fuel through the main jet catches up with the increased airflow. If it's not working the car will hesitate while you accelerate, and may die completely if you floor it, but you should be able to drive around it, as it's not a problem on a constant throttle opening.

Hey Sam,all this wonderful advice.What are you going to do.Bet you wish you never asked now

So finally got around to sorting Hetty out today. I started by setting the tappets. The inlet on the nearside was way out with 0 clearance, so set that to 0.25. I also changed the points and condenser and timed her up, initially statically then used a strobe to fine tune.

All seems well Happy Days

so I know Sam knew what to do and logically worked out the problem

as for the contributors to the 5 pages of increasingly lurid guesses and conjecture, what have you learned

Ive still not learned how to use a strobe properly
Statically works best for me

Easy James,just point and press

However, your engine will work best for you when its ignition advance has been checked and set accurately at operating speeds.