If the exhaust smell doesn't burn your eyes at idle it is to lean
Tell him to please fatten up the idle for one run and see if it is the cure or not
My bracket car runs on E85 with no radiator, it has two small oil coolers for the water. It is hard for me to get heat in the motor in the mornings but once it is warmed up it is harder for me to get it to cool down in a hurry
Most guys that have radiators tell me there cars will cool down around 20 degrees after a 1/4 mile run driving back to the pits If it doesn't that fatten up the idle until it does