My T.T 91 F.S was giving minor problems with poor mid-range running. A new flyer handed me an I.R pyrometer ,we found the mid range cylinder head temp to be 170 F and the max speed temp was 150 F. A small adjust of the low speed needle evened the temps at 150 F and my problems went away. I wonder if anyone out there has used this method for setting an engine. What might the temp range be ? I look forward to the "if's 'n but's "