Cats and carburettors

Cats and carbies.Who'd think that they have much in common. Well they do - if you are talking Weber carburettors. Webers were the carburettor of choice for the world's high performance car brands before fuel injection came along and made them history.
Webers are wonderful devices.They provide instant response and when you open the throttle they make a wonderful sound. But they have an achilles heel.A characteristic they share with cats.
Now as every cat owner knows cats are unpredictable.One minute your favourite cat is lying peacefully purring on the chair beside you.Then without any warning and without any obvious trigger the cat will get up, put its tail in the air and walk off completely ignoring you.
Webers do the same thing.Last week my 2.2 911 Porsche had a full service and the Webers were cleaned and tuned and in particular the idle jets were cleaned. The car is running beautifully. I have just been on a drive up into NSW in company with friend,Craig.
At the start of the drive I had to drive up the motorway to near Newcastle to meet Craig.This meant driving in morning rush hour traffic to join the motorway and negotiating a number of big heavily trafficked roundabouts. Not ideal conditions for a 44 year old car but it could cope. It was running well as it crawled in the traffic and idling quite normally when stationary.At the biggest and most hectic roundabout it was my turn to dive into the very fast moving traffic.No place for hesitation.I was ready to go when the engine just died. It had lost idle. No reason. No warning. I cranked the engine and it fired second try. I waited again for a 911 sized gap.The engine idled away without a problem.
Over the course of the next two days I did 620 km and whilst most of it was fast open road driving on every occasion where the engine had to idle it did so perfectly.
However the idle incident was not the first time it has happened and I know it will not be the last.It is apparently something Webers just do.They have random unpredictability.Just like cats

The Webers of my 911 sitting atop the engine as it idles away quite normally after the long hard drive back this afternoon.There's not a break in the earth wire from the coil.It just turns at 90º away from the camera.

Zoe , the one eyed Himalayan, just thinking about being unpredictable.