A fuel flow meter pays for itself very quickly
Couldn't agree more, plus a multicylinder monitor like an EDM700.
The manufacturer's break-in instructions should be followed, and it is the first few hours that are seriously critical as to glazing.
Otherwise what one needs to do is run at high power until the oil consumption stabilises, which can take anywhere from 10 to 50 or even more hours. In fact I would run at high power (75%) until
all spark plugs cease to be dripping with oil when you take them out.
Most Lyco engines are rated at 100% power (which needs fully rich mixture to reach) continuously and most are rated to run at 75% power at peak EGT.
I had my IO540 rebuild (SB569A) last winter and found it was burning 1qt of oil per hour initially, reducing to 1qt per 6hrs after about 20hrs, and now after about 120hrs it is burning 1qt every 15hrs which is about right, and it is only quite recently that the last of the oily plugs ceased to be oily.
An oil change at 25hrs is necessary, then at 25hrs, then every 50 as normal. And do oil analysis - I use
this very good company. Most people don't do oil analysis, and looking at the AAIB report from one recent totally avoidable multiple-fatal accident there are some whose "maintenance company" doesn't even cut open the oil filter.
For checking the RPM, there is a little program around which you run on a laptop or PDA and it analyses the sound and reads out the exact RPM.