My dial calipers are in mm and roughly I got 1 turn as about 8.25 mm which would be equivalent to .032". But crackedback probably has it correct as one turn equivalent to the .041". I initially used 1/4 turn with the motor on the engine stand but now with the motor installed and run for 10 minutes I will re-check and perhaps preload a bit more. Looks like I could split the difference for now and use 1/2 turn which would help account for any inaccuracies on my part in either direction.