I have been searching the archives but to scant successes regarding thermostats use or lack of use for cooling. I have been having issue with cooling lately. I use to be able to idle on the ramp for over an hour in the middle of a Houston summer with adequate cooling. However, lately temps are rising faster and higher. Yesterday, while troubleshooting this issue I noted that after about a ten minute taxi that the mounting location of my coolant temp probes was reading about 220 degrees measured with a handheld thermo gage, close to what was being indicated on the panel  However, the top of the radiator was cool to the touch. The handheld thermo gage read 45 degrees.   Ok. Seems to be a flow/thermostat/pump issue. I will be Looking into this ASAP. This got me to think about thermostat usage. I have one. I know some do not use them. It is my understanding that if you remove the thermostat you have to close some passage off. What passage is this and why does this need to be done. Also, what is the accepted method. While researching I also saw discussion on restrictive plates. While I am not considering a restrictive plate, the thread discussed drilling holes in the thermostat itself. Lynn mentioned do it caught my interest. It seems this is something I use to know but now forget where I saw it. I just finished reviewing my partial scan of Tracy's conversion manual to no avail and my archive search is giving me hundreds of returns. Thanks, Chris

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