I have that write up on one of my computers. If I find it I'll post it later, but there's an excellent write up by Dubb Jett on his website that explains the correct methodology. The above post will work, but the time on the bench is insufficient. Here's Dubb's link:
[link=http://jettengineering.com/tech/breakin.html]Engine breakin[/link]
It's written for his engines, but the theory is applicable. There's more here (with less detail):
[link=http://www.darrolcady.com/Racing_Info/Tips-tech/tips-tech.html]Cady-Breakin[/link]
this one is directed towards Nelson's.
For a TT40 we're talking running in the 16,000 RPM range to 17,000 RPM on the test stand. Three cautions though. 1) Wear safety glasses 2) Wear ear protection and most importantly
3)
Wear safety glasses!
SD
Here's the Lee Von Der Hey breakin procedure:
.The following steps are highly recommended for successful break-in. First you need a break-in propeller. Use a 9-6 cut down to a 7-6 propeller and make sure it’s balanced. Bolt the engine to your bench or test stand making sure everything is solid. With the throttle wide open and using the break-in propeller you should be running at 13,000 to 14,000 R.P.M.’s (very rich). You will need to run about a half gallon of fuel (15%) at this rpm range to lubricate and loosen the engine up. Run another half gallon of fuel through the engine periodically turning the needle valve in until it reaches about 17,000 R.P.M.’s (the engine should still be running rich). Do not lean the engine out with the break-in propeller !!! Next, remove the break-in propeller and install an A.P.C. 9-6 propeller. Back out the needle valve half a turn and run a tank of fuel through the engine with the R.P.M.’s about 500 R.P.M. down from R.P.M.
peak. You can run a couple more tanks of fuel through the engine to help break it in. At this point the engine should be peaking around 16,500 to 17,000 R.P.M.’s. Now you are ready to race the Thunder Tiger .40 Pro. Bolt it on your favorite Q-500 racer, set the engine 500 R.P.M.’s down from its peak R.P.M. and turn it loose.