340 break in question

I let the engine warm up to full temperature before going to 2000 RPM or revving it.... I keep it at 1000 - 1200 RPM until it reaches temperature and the thermostat opens...

85% - 90% of engine wear happens when the engine is cold and the friction is higher... The faster you rev it, the more forces are on the moving parts, especially the ones with shear (rubbing) force acting on them... When you let the engine warm up before letting the rpm's get too high, it will last longer.... When the engine warms up, the friction goes down and less wear....

My #1 rule: NEVER REV A COLD ENGINE!!!!

If you rev a cold engine you increase the wear on the bearings, cylinders, crank, cam, etc.... Warm it up first, then rev it all you want....

Do you jump right out of bed and run a mile immediately??? No, you wake up, drink some orange juice, stretch a little, then run...

Same with an engine, it needs to warm up....