Trying to get the '76 308 to pass the California smog test. Options include buying a Colortune and adjusting the air/fuel for a blue flame. Question whether or not I can even use a Colortune on a 308 considering the sunken spark plug holes. Also, does a blue flame guarantee the leanest air/fuel mixture? Also, is Gastester a better device to use?
A number of people here have used Colortune on the 308 2V series. A certain mechanic that has been banned from this board uses them. <g>
I had mixed results using up to 4 of them on my 308. It's very hard to see the combustion effects on the 5-8 bank. I also saw a lot of mis-firing on some cylinders or with some color tunes. I was unable identify the causes. I may have better luck with the new carbs I recently installed. A gas tester may also be a good tool to use. The down side is it is best used upstream of the catalytic converters. The best case is if you can use it in conjunction with the factory sampling tubes that insert into the individual header branches. This method is the only one worth trying IMO. Sampling in the collector, but upstream of the cats, you would get an average reading of 4-cylinders.
Vincent, A Colortune is a special spark plug with a clear insulator that allows one to directly view the colour of combustion. A yellow flame indicates a rich mixture, a blue flame indicates a nearly correct mixture. There are of course shades of each. The down side of a color tune is that it is fragile so it is limited to low load conditions (idle and off idle), has limited heat capabilities, is prone to fouling, and it can be difficult to view. When it works, it can provide valuable mixture data for an individual cylinder, in real time.
