Weber carb problem

[chrishewett]

I fitted a pair of webers at the weekend which I had bought on ebay. They have been completely refurbished and look very good. I found that the float level was very high so I reset that. The car runs very well on them, much smoother than before but now the problem. I cant get the engine to idle. The revs will not go below 1800. The throttle is on the stops. When I checked them over before fitting I am sure that the throttle plates were completely closed. I will take them off again tonight but meanwhile is there likely to be any other reason other than the throttle plates being slightly open? If the plates need adjusting any advice?
Chris

[theelanman]

I know this will sound very obvious but have you checked the tension in the throttle cable......ie youve not over tightened the cable so that when the pedal is at rest the carbs dont close fully.....
I know youve probvably dome this and that its a stupid comment but I know that Ive done it before in my eagerness.....and the obvious sometimes passes us by as we are sure that we're ontop of the situation...

just a thought
cheers
G

[john.p.clegg]

Chris
No need to take them off (it is backbreaking) just use a torch and small mirror.....
John

[kayenney]

Don't get nervous - "Torch" is English for "Flashlight"!!

[gjz30075]

Could also be a vacuum leak. Check around the mating surfaces of the 'O' rings.

Greg Z

[bill308]

There is also a possibility that the throttle shafts are slightly twisted preventing the outboard butterfly valves from fully closing. It's also possible that the throttle plates were disturbed or replaced at some point and are not perfectly centered in the bores. A good air flow meter like an SK Synchrometer or better yet a manometer measuring manifold vacuum might detect this or other vacuum leaks. Overly advance ignition timing due to too much static advance or sticking advance mechanism can also cause a high idle. I hope this helps.

[john.p.clegg]

No.
"Torch" is English for torch,
"Flashlight" is American for torch.

John

[chrishewett]

Thanks for the tips.
I checked with a " battery powered hand held light" and the throttle plates appear to be closed. Roy at paul mattys suggested air leak so I have checked with the usual water/wd40 around the O rings and also blanked off the manifold to servo and headlights but with no results. The timing seems to be ok and hasn't changed since I swopped carbs.
Could the fault lie with the starter device not returning? I suppose I will have to take them off again but I am not hopeful, I will probably end up replacing the original carbs. Reluctantly.
Chris

[bill308]

Chris,

Unforrtunately, eyeballing the fit of the butterfly valves in the bore is not sufficiently accurate to determine if the fit is acceptable. Very small air leaks can cause high idle problems.

Bill

[chrishewett]

Thanks for the tip Bill, I will take them off tonight and have a proper look.
Cris

[Hamish Coutts]

Chris,

If you ae taking your carbs off tonight why not revert to your 'battery powered hand held light' to check the fit of the throttle plates.
Put the lights out then hold the torch up to the opposite side of the carb from you, close in so you don't dazzle yourself. If there are any gaps in the fit of the throttle plates, they will be obvious.

Hamish

[M100]

As long as the 'battery powered hand held light' is not made by Lucas

[Hamish Coutts]

Never a truer word said Martin. It would probably flstten the battery very quickly, with a lot of noise.

Hamish.