Originally Posted by KeithB
I have a Superior XP-400 with dual P-mags. I installed the jumper (less advance) to help keep temps under control during break-in. After about 30 hours when it was clear I did not have CHT issues, I removed the jumper for max advance. The engine provides great performance, excellent CHTs,and runs very well lean-of-peak with very nice efficiency. I’m curious why do you say this advanced timing is way too much for an angle valve engine?
That is not a good setting for your engine and you could be giving up some power, and risk damaging your engine.
What is the recommended timing for your engine? I belive it and the IO-360 & 390 angle valve engines are designed for 20° BTC timing settings.
The "Jumper In" A configuration starts at 26.6° and the "No Jumper" configuration starts at 30.8° BTC for high power operations, such as takeoffs and they advance from there.
With parallel valve engines, we have been able to demonstrate better performance and cooler CHT's with slightly reduced advance settings.
I suspect you will pick up some performance and reduced fuel burn, if you customized your timing configuration close to the recommended 20° BTC.
I will be happy to work with you (or anyone else with an Angle Valve engine), to prove this out. Just PM your number, if you are interested.