[ceslaw]

Aircraft often have EGT (Exhaust Gas Temp) indicators to help adjust the fuel mixture to compensate for changed in altitude. A simple gauge may have only one cylinder temp indicator while others have a series of 'bar graphs' giving an indication for each cylinder.

So it seems reasonable that using an infrared temp indicator would be useful in tuning the Webers. It won't be as accurate at an EGT, but may give a good relative indicator.

My modest 302 (375 hp) headers typically run around 250 degrees at idle. But when one cylinder was running 350 - 400 degrees I turned out the mixture screw a quarter turn to make it a bit more rich. The occasional popping immediately diminished. This is certainly not as accurate as O2 sensors, but it can be useful in my judgment.

What is the ideal temperature? I doubt there is a single answer. There are too many variables based on engine design. But as a relative indicator to let one know if a cylinder is too far off it may be useful.

I see not point in trying to get the temps closer than 50 - 75 degrees. It is just not accurate enough. But if one cylinder is running 30 % higher than the others, it is likely too lean.

I am curious as to the experience of others using this technique.