Series3 petrol engine(weber) cutting out

(I posted this in general bit before I saw specialist series thread so will try and delete other post)
Hi, I'm a newbie so pls go easy on me if i make a faux pas or etiquette blunder..
My series 3 109 (1978) 2 1/4 petrol started stalling when lifting off the gas.. it idled okay (just) so thought it might just be a carb blockage rather than a problem with idle jet ( I have 3yrd old weber replacement carb) now it won't idle and cuts out whenever i'm off the gas pedal - any thoughts, feelings, ideas before i take it to the shop.. i'm a clumsy (and sweary) mechanic, but can attempt simplish tasks..
Thanks,
L

Have you tried lifting the tickover by screwing in the throttle stop screw?

A little trick of the trade is to start the engine up with the air filter off,rev the engine to 2-3000rpm from under the bonnet and put your hand over the top of the carb,it'll feel like it's gonna suck your arm off but don't worry it won't,the engine will start to die and kick black smoke out,keep your hand over the carb untill it nearly cuts out and then take your hand off,it will cough,spit and fart and run like a bag of crap for a few secs then clear.(you will have to rev it to keep it going and clear)Do this a few times and if there's any crap in the jets it'll all be sucked out

great tip thanks.

another one! mine still does it even after having it suck my hand off

check fer air leaks and things as well.

mine's worse now it's cold and/or wet....

spent the weekend making an adaptor for a nice big SU. will see if that fixes it

Yeh it dose'nt always work,but it's worth a try before you start pulling the carb in bits

Many thanks - will have a go today.. don't think it's tick over as it stalls the moment you lift off the gas.. something bad is in there and it's gonna come out!!

i had that problem on a zenith carb.....ended up being the needle had came loose.....once i realized this it was an instant fix

definitely worth a try with V8jon's method - doesn't half suck hard though! also check the baseplates aren't bendy as bannanas - if there is a leak, its on the overrun when it'll be the most obvious

I've fixed it with a big SU

from a 8V K series rover metro, bit of building an adaptor plate and job's a goodun. needle looks about right too

hi
it might be icing up....