From: dingbat@codesmth.demon.co.uk (Andy Dingley)

>I'm at a loss as too how a clear insulator is going to help with
>diagnosing carburator problems..... either there is a good spark
>or there isn't.  

It's not an electrical diagnostic tool, it's a fuel/air mixture
diagnostic tool. Think back to a chemistry lab Bunsen burner for a
moment - when you open the air sleeve (weak mixture) the flame is hot
and blue. When you close the sleeve (rich gas mixture), the flame is
luminous yellow and sooty.

It's just the same in a car engine. A blue flame is a good mixture,
orange is too rich and white or pinkish is too lean. Snapping the
throttle open should give an orange flash as the accelerator pump does
its thing. One cylinder with white flashes tends to indicate a leaking
inlet manifold gasket.

I use four of them because I have a V8 with two single choke carbs and
a manifold design that has 2 long and 2 short branches from each carb.
By using a plug in each combination, it's easy to get the mixture
adjusted right on each carburettor - I've never managed to do it with
my exhaust gas CO meter.

Don't go for a road test with Colourtunes in place. They _will_ melt
if you hit them hard enough.