[nymack66]

I install a rebuild power head , during the break 24:1 oil premix , If I run the engine for hours variable throttle the engine runs like it should, shut-off fires right back up , however if I let it sit for 15 to 20 minutes it will not crank period , manually turn the engine my hand tight i can feel it.
Once it cools down from 145 degrees to 120 degrees it fires right up
Question is is this normal ?
I am certainly not overheating since 145 degrees for a block that is just shut-off I have new gauges and senders installed on both starboard and port side of the block , At the time of the shut-off the temp is 130/125 , with the engine off it rises to 135/145 that's when it locks up not even the starter can turn it .
Should I be concerned or this is normal ?