John deakin engine management & ignition

I agree that these articles are most pertinent to operators of large fuel injected engines such as my IO550 Conti but there are loads of little gems for everyone in there. He does mention carburettor engines but not much. And, before a lot of this makes sense you need GAMI injectors and at least an EDM 700. Here are a few of the little gems I made a note of:

Don't bother cycling the prop on a constant speed prop on run up. Just look for red line RPM as you start your roll full throttle.

LOP for HP multiply fuel flow in GPH by 14.9. This does not work ROP. 14.9 is the figure for 8.5 compression ratio.

1250 - 1320 EGT on take off should be correct. If higher the max fuel flow is too low. Have it reset.

Outside the Red Box

At 65% power, use richer than 100 ROP, or leaner than peak EGT.
At 70%, use richer than 125ºF ROP, or leaner than 25ºF LOP.
At 75%, use richer than 180ºF ROP, or leaner than 40ºF LOP.
At 80%, use richer than 200ºF ROP, or leaner than 60ºF LOP.

This last one is particularly relevant to me as I had to have a top end overhaul at 350 hours, albeit Conti paid for the parts and the work, not the removal and refitting:

Unfortunately, we need to separate all the "flat" (horizontally opposed) engines into two groups. One group is all TCM engines manufactured since about 1991, and the other group is "all others."

Something changed in TCM engines in about 1991. I cannot tell you for sure what it was. It may have been the "choke," it may have been a change in the machining processes. It may have been changing to a different method of installing valves. TCM essentially threw away all the old machinery that had served so well (if inefficiently), and installed all-new, modern machinery. They had a strike that resulted in management assembling engines for a time, and they lost a lot of their senior engineering talent. But one thing seems clear: It's a very, very rare TCM engine that lasts more than about 400 to 700 hours without major cylinder work, if the cylinders were made since 1991.

Mostly interesting and often controversial.

Ian