You have one engine. My goal is to see the engine as my friend.
- above 75% power, no leaning.
- at 75% power, 100F on the rich side of max readout EGT.
- at 65% or lower power, 100F on the rich side of max readout EGT or on the
lean side of max readout EGT.
The goal here is to stay away from max readout EGT.
Gustav, I'm sorry, but there is no reason to think you're doing your friend a favor by staying away from peak EGT, or remaining full rich at WOT.
To the OP's question, Lycoming does not specify a maximum EGT for the normally aspirated engines. And they have long recommended "best economy cruise" as peak EGT, allowable at anything less than 75%.
As for WOT, a Bendix type injection, in theory, meters fuel in proportion to the square root of air density. As such, it does a fair job of
leaning itself as air density is reduced in the climb...but it's not perfect. I've measured my FM200, knob full rich, WOT, 200 to 15K feet, and the "auto enrichment" effect is there. The operator
must lean in the climb if full power is desired. The constant EGT method works well.
Lycoming's leaning guidelines are ancient. More recently, we've seen interest in reduced valve sticking. The leading theory is condensation of lead oxides, and the suggested preventative is keeping gas and surface temperatures high. I'm not aware of any hard research on the subject, but right now practically everyone in the industry will ask about your leaning methods if you show up with a stuck valve...and the goal isn't
low EGT.