I heard my hangar neighbor swearing so I went to see why. He's got a 1997 M20K with a TSIO 360. He and his mechanic are trying to time the left magneto and the lower mag holdown nut is impossible to reach. I tried for a while and can't see a way to loosen it.
Any Mooney guys here with TSIO 360 knowledge?

Cross post on Mooneyspace and you’ll have your answer in a couple of hours. Experienced Mooney A&Ps post frequency on the site and there’s a ton of technical knowledge. Friendly place. No personal experience with the TSIO. General theme is accessory’s are in a very tight space.

That's not as bad as some of the conversions where they cram a 520 in where the 360 was. I looked at one the other day, and you almost needed an inspection mirror to see a magneto.

Can the mag be rotated one gear tooth to get better access?

Both magnetos are a pain in the neck to get at. Some disassembly is required. As for the left mag, it’s better to first remove the #2 alternator. I ground down a wrench to access that hold down nut. It was the only way I could get on it.

Removing the alternator did the trick. The timing is supposed to be 20* . The right was 21* but the left was 24.7*.
Thanks to everyone for the responses.

You would be advised to remove the mags and do a thorough inspection.

Mag timing does not change without a reason.