Breaking in rebuilded engine

[BenR]

That is the correct way to bed an engine in.

When you build an engine you set all the tolerances to specific oil clearances, there is no point doing this if your predicting metal on metal contact between any surfaces, as such, bedding in does not need to be done.

The only thing you have to worry about is ring seal efficiency, and Fii and Ivan are 100% right in saying you need to induce high throttle angles to generate cylinder pressures high enough to increase ring tension on the cylinder walls. If you do not, within minutes its pointless.

Do not run in with synthetic, run off synthetic for at least 1000 miles, but change at 100 miles for new mineral oil with NO additives in it.

Use 80% of the rpm range and 100% of the throttle range within the first few miles of warming up, it only takes a few WOT runs to bed the rings from brand new if you use 100% throttle.

Dont be scared, if it was build properly there is no problem

On our dyno we start them (they are pre-heated), get them upto oil pressure, check at 3000rpm, then increase load to 100%, lower it and run it in for 1 hour........then that is done.