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Collection, Preservation and Display of Old Lawn Mowers

Loose mixture screw Dellorto 20 13 A carb (Atco Commodore B14)

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Hi,

We are at the last stages of restoring a B14 and while assembling the mower and getting it running I found out that the mixture screw is somehow loose and there is no spring to keep it in place. Result: from vibrations of the engine it comes out of the carburettor. From drawings of the car there is no clear indication if there is a spring there at all. The 20 13 carb which I have from a Qualcast CPS35 has a bigger screw with a spring. Could someone tell me that it should have a spring or not??

As a workaround I used 542 to keep it in place at the moment.

 

Forums

Chris G Thu, 11/07/2019

No spring per mine. It is likely to be coming loose if the rubber ring on the screw is no longer providing resistance, I think you just need to change that o ring

 

wristpin Thu, 11/07/2019

As per @Chris G, try a new O ring. I can’t say for certain but I believe that in certain applications there was a plastic “ anti tamper” cap covering the screw orifice.

Henno Fri, 12/07/2019

Good morning Chris and wristpin,

Thanks for the speedy answers, just what I needed, Iam going to order a new o-ring,