Plug colouring

[blitzracing]

I used to set my fuel mixture by doing plug chops, and checking the plug colour. Dark brown too rich,tan just right, white too lean etc. Modern engines and fuels dont seem to show this colouration- now its white as normal, or black soot if rich. I assume this a function of cleaner burning fuels ??

[stevieturbo]

Its a combination of hot plugs, and lean mixtures, for good emissions etc...


If you want to monitor mixtures, buy a wideband. Trying to read plugs, relies on too many variables.

[Boosted LS1]

I used to look deep into the plug for the corona. I also look along the earth electrode. Thing is, plug chops on a car always seemed horrible when compared to a yamaha. For some reason cars, well my car used to hate it!

I'd agree with Stevie, a lambda is a far better solution.

Boosted.

[leorest]

Ahhh reminds me of the good old days spent peering down a Gunsons colour tune TBH I found looking at the colour of the tail pipe(*) after a good run about as good as looking at the plug itself. Modern technology is obviously the more accurate/expensive route compared to the old school subjective/cheap method.
(*)Obviously before the days of cats, or fuel injection for that matter