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roger_abbott
Jedi Hopeful
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I've worked with SU carbs for 30 years on my Jags, MGs and Healey and I have never seen anything like this. The dashpot damper rod fits inside the dashpot chamber before you can get the cap low enought to screw it in. You probably should check to see that there are no foreign objects inside the chamber that could restrict the piston from rising. I would not repair or re-use the damaged part - it's not worth the risk of further damaged to more expensive parts, such as the engine coming apart at 10,000 rpm.
My recommendation: remove the dashpot assembly (the dome) and the piston from the carburetor. Clean out the dashpot chamber (the slender tube coming up from the center of the piston) and make sure there is nothing inside it. Replace the piston in the carburetor body, replace the dome (without the return spring) and check that the piston falls freely against the bridge of the carburetor (the raised part where the jet is located) when you lift the piston slightly. If the piston clicks against the bridge, remove the dome and replace the return spring. Don't attempt to change the length of the spring. It is part of the calibration of the carburetor. Next, insert your brand new dashpot damper. There should be little or no change in the behavior of the piston when you lift it and let it go - you should still get a click. If you do, put oil in the dashpot and you should be good to go.
My recommendation: remove the dashpot assembly (the dome) and the piston from the carburetor. Clean out the dashpot chamber (the slender tube coming up from the center of the piston) and make sure there is nothing inside it. Replace the piston in the carburetor body, replace the dome (without the return spring) and check that the piston falls freely against the bridge of the carburetor (the raised part where the jet is located) when you lift the piston slightly. If the piston clicks against the bridge, remove the dome and replace the return spring. Don't attempt to change the length of the spring. It is part of the calibration of the carburetor. Next, insert your brand new dashpot damper. There should be little or no change in the behavior of the piston when you lift it and let it go - you should still get a click. If you do, put oil in the dashpot and you should be good to go.
