Now that was a surprise- Carbs

[terry]

Just when I thought that there was nothing about Lotus Cars (CC's preferred plural) that I couldn't sort.

For ages now, I could not figure out why two of my cylinders are constantly blackening plugs and obviously running rich. Check the tuning, jets, float levels, then realised that on the very rare occasions when I pulled the choke, it just moved a bit.

Not a problem, because nobody uses the choke, anyway I hear you ask.

BUT, (there's always a BUT).

When I pulled it all apart, I found the problem.

When you DO pull the choke cable, it operates the two levers, which turn a cylinder, with a steel offset pin in the end, that lifts a brass rubber ended plunger, from the carb body, allowing more fuel in hence the choke.

Here's where the BUT comes in.

The brass plunger was seized solid, (some time in the distant past), and the steel pin
had ground a semi-circle into the brass.

This gave the impression that the plunger was moving when in fact it was stuck half way up.

i.e. choke on one carb, permanently half on.

Fortunately, I found a spare plunger, cleaned the carb body, so all is now well.

But if you need to check that plunger does in fact move, undo the big brass nut at the top of the choke cylinder, operate the choke, and see if it moves.

This is a classic case of Shrodinger's Cat (check google), never assume something is doing what it is supposed to, until you have actually LOOKED.

Terry