J.P. Instruments EDM 740 Pilots Guide - Manual (Page 30)

Page 30 Engine Data Management
Cruise - engine stabilized & leaned using LeanFind
Suggested setup:
Percentage view
Automatic mode
Be alert for:
 uneven EGTs or CHTs (carbureted engines).
Make fine adjustments to throttle, then RPM,
then mixture to level the display columns.
 abnormal patterns of EGTs and CHT. (see
“Diagnosing Engine Problems” on page 32).
Descent .
Suggested setup:
Percentage view
Manual mode
Be alert for:
 CLD: shock cooling alarm default is –60°F.
Average cool rates of –40°F/minute to
–60°F/minute are normal, depending on the
engine size.
Shock Cooling
Cooling the cylinders too fast can result in cracking and eventual failure.
Lycoming Service Instruction 1094D (March 25, 1994) on Fuel Mixture
Leaning Procedures states:
“At all times, caution must be taken not to shock cool the
cylinders. The maximum recommended temperature change
should not exceed 50°F per minute.”
JPI checks shock cooling on all cylinders. The EDM automatically
displays the cylinder with the highest rate of cooling.