First of all, engine tuning is really hard at the track. Even the best pros like Jared Tebo will typically go 2 mi. away from the track to an empty parking lot just to make sure his engine is tuned right for a race.
Here's a simple method. Set the top end by sight and sound.
Sight: There should be a thin wisp of smoke coming out of the pipe. No smoke= too lean, cloud of smoke= too rich.
Sound: You should also not hear the "blubbering" sound that the engine makes when it's too rich. It should have a clear, distinct tone of the engine without the pinging sound of being too lean. Experiment with this in an empty parking lot where you can hear the difference.
After the top is set do a high speed run to make sure the engine is cleaned out. Then go full speed towards you and stop the car quickly within 10-15 ft so you can hear it well. If the engine goes straight to idle, you're ok. If it is running fast still while at Neutral (aka "running on"), then richen the bottom end.
Next do a punch off from dead stop. If the engine blubbers, makes lots of smokes, and slowly takes off, then it is too rich on bottom. If you've just richened it because it was running on, then maybe your top end was set too lean and you should re-check it.
If it hesitates on the bottom and blows no smoke on take-off, that is called a "lean bog" and you should richen the bottom end.
This is my general rules of thumb. You should not go by a temp gun except to confirm that you are tuned correctly. My normal gas truck is around 190-200 F, for 1/8th 220-230 F.
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