Advancing Slick Mags Settings?

As my mind wonders about timing an engine, I asked an A&P friend; "If 25 BTDC is optimal when running 100LL, why not time it at 28-30 BTDC when running mogas? Would this help get more power out of the engine if advancing the timing is a good thing with EI?"

This is on my 0-235 -3.

I guess I could always try it and report the results, but I thought I would ask the much more knowledgeable VAF crew first.

Larry, I recommend that you do not try this. To prevent detonation, lower octane fuel may require that timing be retarded - not advanced.

I have a Superior XP-360. The manual requires timing to be set at 25 deg BTDC for 100LL. It recommends 22 deg BTDC for 91 octane auto fuel.

Luis Luciani

Luis is spot on.

Do not do it.

100LL burns slower, therefore then spark advance being more with Avgas.

osxuser said:

100LL burns slower, therefore then spark advance being more with Avgas.

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Ah! This advice makes sense. I guess my mind wandering can be a dangerous thing!

Thanks guys!