The tailpipes are a good indicator of how the engine is running. Dorton says they should b
A quick visual inspection of the tailpipes is also a good way to get an idea of how the engine is running. Dorton says he usually carries a flashlight to help him see inside the tailpipes as far as possible, but as long as you can see approximately 12 inches up the exit of the pipe you should be fine. If all is well, the inside of the pipe should be light chocolate color. The color is from the carbon deposits from the exhaust. If it's white or ashy, that's a sign the engine is running too lean. If it's dark or excessively sooty, then you're probably running too rich. Sooty pipes can also signal a blown power valve. If they're oily, that's a sign you may have a ring sealing problem.
One area that often leaves many engine tuners barking up the wrong tree is trying to read plugs at a short track. Dorton says that there is simply too much idling and off throttle driving that it contaminates the porcelain on the plug and makes an accurate read too difficult. "Plus," he adds, "to get a good read, you need to do a clean shut off, where the driver kills the engine while at full throttle. But most Saturday night short tracks aren't set up for green-flag pit stops like you're used to seeing in NASCAR's Sprint Cup Series. The entrance to pit road is often tight with very sharp curves, and cars can't coast all the way to the pits. It's just too dangerous to ask a driver to do a clean shut off at most short tracks."
What you can do, however, is keep an eye on how much heat the plug is seeing. The farther the heat ring travels up the plug, the more heat your engine is seeing. This is something that changes from engine to engine, so you'll have to get an idea how heat discolors the plugs on your engine. But, for example, if you pull a couple plugs after practice and notice that the heat ring extends all the way up the threads of the plug, it's a sign that your engine may be running too lean.
Use these tips as guidelines to ensure that your engine is in top shape when you get to the track. Remember to always be thorough in your inspections and keep detailed notes.