Weber 34 ICH Problem

[Labradors]

Hi All, I have had a Weber 34 ICH carburetter fitted to my 1971 2.25 petrol S3 for the past 6 years with minimal problems until a blocked idle jet last month, I took the carb off the manifold, stripped it and compressed air cleaned all orifices, galleries, jets, checked float height & needle valve condition. Renewed the in-line petrol filter.

Since that strip down & reassembly all is well with the running and performance BUT with the engine warm if I park up and switch off for 30 mins on restarting the engine it runs way over rich with black smoke for a couple of seconds, then clears and runs normally. Its just as if the carb dribbles into the manifold from the float chamber when warm (this does not happen starting from cold) My very first thought was not carb connected but valve guide seal wear, so I fitted new ones but it made no difference and problem persists.

I would welcome any ideas ?

[Labradors]

Hi All, I have had a Weber 34 ICH carburetter fitted to my 1971 2.25 petrol S3 for the past 6 years with minimal problems until a blocked idle jet last month, I took the carb off the manifold, stripped it and compressed air cleaned all orifices, galleries, jets, checked float height & needle valve condition. Renewed the in-line petrol filter.

Since that strip down & reassembly all is well with the running and performance BUT with the engine warm if I park up and switch off for 30 mins on restarting the engine it runs way over rich with black smoke for a couple of seconds, then clears and runs normally. Its just as if the carb dribbles into the manifold from the float chamber when warm (this does not happen starting from cold) My very first thought was not carb connected but valve guide seal wear, so I fitted new ones but it made no difference and problem persists.

I would welcome any ideas ?

Further to the above problem. A cure has now been found which might be of use to other members.

On advice given by a Series expert on another site. I lowered the float closure height by 2mm, on reassembly I had to readjust the slow running mixture and idle speed but it seems to have cured the over rich warm start up.