head scratcher!!!

Had a friend with this problem in a BB Challenger. He was convinced he had some sort of electrical gremlins. We chased everything thru, no voltage drops/bad connection/missing grounds. Battery was fully charged and alternator put out a good charge. Car would start fine when it was cold, but warm, it would groan and barely turn over. Found out his engine was so tight that when it warmed up, you could barely turn the engine over with a bar! Cold, the clearances loosened up and you could turn the engine easily.