IMO, 1800 is low for break in. I prefer varying between 2500-4000 for 15 minutes. The two biggest reasons are first, obviously you don't want the engine to idle or RPM too low, because you have the risk of wiping a lobe. 1800 is not much above fast idle when the choke is on.
Secondly, you want to sling a LOT of oil around and you're not going to accomplish that by letting the engine run slowly.
