We tend to call these things dashpots in the UK. From your mention of four
screws, I'm assuming it's a Stromberg carb so here's the procedure.....
1. Scribe a mark on the lower edge of the dashpot, crossing onto the carb.
body so you can replace the dashpot in the same orientation (some carbs will
already have such a mark). Remove the damper unit.
2. Carefully lift the dashpot off the main body. The piston (air valve) will
probably stay in the carb body. The main danger is dropping the piston,
thereby wrecking the needle.
3. Inside, you'll find a spring, possibly a concentric ring and the rubber
diaphragm attached to the piston. The spring's too feebel to fly very far
but take the opportunity to check on the state of the diaphragm.
4. Buff away to your heart's content.
5. After replacing the dashpot, check that the piston will still fall down
to its lowest position with a soft click. If it won't, you'll have to
re-centre the jet.
6. Repeat on other carb.
7. Have a small preen.
These alloy dashpots shine up really well. On the Practical Classics Minor
Traveller, we had an SU carb which had been factory reconditioned. The
dashpot had been polished to a faultless mirror finish.
All the best, Dave Hill
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