I have a new HRE motor with 10.5 plate. David from HRE idled one tank through it. Then told me to run 1 tank at 4K RPM without the belt and another at 8K RPM with belt on to get some resistance. After that put a lot of laps on to get it totally broke in.
There was a thread on this if my memory serves me right....thinking some used a prop to break it in....me, myself, thinking Jerry have the right idea :thumbsup: :thumbsup: Idle a tank, and floor it !!!!!
The biggest thing with a break in is to seat the ring. I use a prop to provide a load and use regular 30wt. non detergent motor oil mixed with regular gas. Synthetic oil does not allow the ring to seat as quick. Mix 6oz. oil to a gallon of gas. Set the carb a tad rich and let the motor come up to temp then crank it up and let it run thru a tank of fuel 8 ounces or more. Now, let the motor cool down. check it over and when cool fire it up and repeat the procedure above. After a quart of fuel you should be ready to put in the car and go for it. It will get a bit stronger on each run. Don't run it too lean when breaking in or when racing.
Second method is mount it in the car and run it. This takes much longer to seat the ring but it will eventually come around.