Plug colour reading

[mike1980ra40]

heres a spark chart on my webspace ..

http://www.users.on.net/~mse/forum/sparkcolourchart.jpg

[jeffro ra28]

From personal experience reading unleaded plugs is a bit more tempramental. They tells lies!
For methanol or avgas you get true signs tho! Also, adding octane booster(with avgas) gives a much stronger tan colour!

Just know this tho, the cad coating burns of at around 1550 F so when you rub back the suit and the cad has burnt of then your are definantly to lean! Most of the time the cad will just turn a nice goldy colour but you will know if its burnt off!