Hi, first things first. What does the engine owners maintenance manual say to set it at? That should be the definitive source. While you're looking that up, I'll send this to our A&P, Erich Rempert for his comments. Please stand by.
Wright Brothers Master Pilot, FAA Commercial Pilot
Aviation Director, Piper Owner Society Forum Moderator and Pipers Author.
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I agree totally. What a novel and unique approach to tugging our airplanes. Of course, if you live in Florida it might not work so well, lol. Have a great weekend!
MSN? Really? I'm just south of Milwaukee at BUU! We're neighbors!
Yes they do. I'm at the home of Knots2U. I could spend all of my money there, lol Have a great weekend!
Here are comments from our A&P, Erich Rempert:
28* is not legal or recommend. However 3* is not an outrageous amount of timing to be out of spec either. Many mechanics would not choose to adjust the timing if it was off 3*, but it really depends on the application.
A turbo supercharged engine with the timing advanced 3would be a potential problem I'd address, the possibility of detonation and catastrophic engine failure is too high to leave it. If it were 3 retarded it would be safe but performance would suffer perhaps by 10-20hp.
On a J-3 cub with an A-65, I'd set the timing where it ran best...
I suppose your "eye" is best when it comes to your airplane...
(But I wouldn't adjust my eyes much more)
Erich does mention above that with 28 degrees you have the possibility of detonation or catastrophic engine failure but you also gain 10 to 20 HP. With it turned back to 25 degrees, the engine is smooth and safe but at the cost of 10 to 20 HP. The extra HP aren't normal and you're overdriving the engine, causing you the potential of losing it.
I just purchased a PA-28R-201T. I'm very happy with it.