The Bess method of breakin (also called the Heat Cycle Method)


From the very 1st time you start your engine, plop the car on the
ground & begin running it in a parking lot in 2-3 minute intervals,
tuned only *slightly rich* getting the temps up in the 200F range on a
normal day. Every 2-3 minutes, shut the engine down & let it cool
completely with the piston at BDC, and then fire it back up; continue
this cycle until you've run 15 min or so, and then bump up to 3-4
minute intervals. Vary the RPM and don't be afraid to get the temps
in the 200's. What you want is heat cycling of the components without
the incredible stress that comes with breaking an engine in when it's
overly rich & cold. After cycling the engine in this manner for about
20-25 total minutes, it'll be ready for the track and race tuning.