Not necessarily- - - -all compression testing is simply a percentage comparison of compression pressures between individual cylinders. Less than 5% is good- - - -over 10% is bad. Warm, cold, or somewhere in between doesn't matter. Conventional compression tests are roughly equivalent to "Measure with a micrometer- - - -mark with chalk- - - -cut with an axe!" The adapter is simple- - - -knock the porcelain out of a junk spark plug, thread the steel shell with a 1/4" NPT tap, and screw an air line male quick connect fitting in. Then hook up an air hose from a regulator. So simple even a Marine can do it!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!