Weber Carbs

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John Nash
Posts: 8
Joined: Mon Dec 24, 2018 5:14 pm

Weber Carbs

Post by John Nash » Mon Dec 31, 2018 12:48 pm

I have had trouble with my cars slow running. On investigation the large anti vibration spectacle mounting plates that have two rubber O rings were found to be perished. I assume this has been caused by the additives in the modern fuel. I have sent an enquiry to Weber's but have not received an answer yet. Has anybody else had this problem? Now I cant balance the carbs so has anybody got a recommendation where I can take it in the east Kent area. Sandspeed of Bexley set the carbs up originally but I don't want to go all that way if there is somewhere closer.

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Ian
Posts: 37
Joined: Sat Dec 01, 2018 12:50 pm

Re: Weber Carbs

Post by Ian » Mon Dec 31, 2018 3:12 pm

Hi John,
Are these twin weber 40's you are talking about?
Are the mounting plates the type with a groove and O ring on each side? or the "misab" type with a single O ring bonded onto the plate?
I didn't have too much trouble with mine but the O rings did seem to swell with the effect of fuel - it will be interesting to see what Weber have to say.
What problem are you having balancing them? I have a synchrometer if that will help.

John Nash
Posts: 8
Joined: Mon Dec 24, 2018 5:14 pm

Re: Weber Carbs

Post by John Nash » Tue Jan 01, 2019 3:27 pm

hi Ian
The anti vibration plates are the ones with the bonded O rings. I think the slow running problem I have got is to do with fuel imbalance between the four chokes. The suction values per cylinder are OK as I checked these with my home made manometer. After reading the Weber book again I will have another go. What they say is to pull off each lead in turn and note the rev drop, before reattaching and making the adjustment to the slow running jet. The problem is that it is quite difficult to pull off and reattach the leads while the engine is running as there is a danger of breaking the extended electrode and insulation shroud whilst wearing thick rubber gloves. What I may do is use an old set of leads and make an insulated shroud big enough to get hold of when wearing gloves. I may add that getting a HT shock is not a nice experience.

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Ian
Posts: 37
Joined: Sat Dec 01, 2018 12:50 pm

Re: Weber Carbs

Post by Ian » Tue Jan 01, 2019 3:49 pm

I have a colourtune (or two) if that would help with setting up the idle mixture.
If you are getting shocks off the ignition leads, are they ripe for replacement?

John Nash
Posts: 8
Joined: Mon Dec 24, 2018 5:14 pm

Re: Weber Carbs

Post by John Nash » Thu Jan 03, 2019 5:58 pm

Thanks for the offer but I can't use a colour tune as the spark plugs are down a long tube through the rocker cover and the transparent end of the colour tune plug cant be seen. I am using a special double insulated set of plug leads that I made up just for this adjustment so that I can hold them without getting a shock. My leads that are usually fitted are new with the correct insulated top hat piece that the plug lead shroud pushes onto but these are made of a brittle material that can be easily damaged if pulled off and refitted while the engine is running.

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