Reference TDC mark for IO390

My new engine comes with a light weight SKYTEC starter which looks a bit different than the SKYTEC that I have seen on most other engine. One other difference is that there is no pin hole for the timing mark and was wondering if IO390 has another reference point to line up TDC with.

timing mark

The 14 I've flown has a very tiny hole in starter for timing however you can use the timing mark on the aft side of the 'flywheel' & use the split line of the crankcase as the engine reference point too.

Back side of your ring gear has a full set of timings marks, yes? Case centerline is the reference.

Thank you guys, I do see the timing mark on the ring gear but did not know the reference mark which on my IO360 was tiny hole on the starter. From this, I take it that the case split line on top would be my reference point with the TDC. I was planning on verify by physically checking the piston on #1 reaching the top of the cylinder.

Interesting part, for the starter, it is listed as Harzell starter and I am not sure if Harzell has bought SKYTECH or a mistake in the parts list that came with the engine.

Hartzell bought both PlanePower (alternators) and Sky-tec (starters).

I highly recommend this tool. No timing marks needed. Both, my IO-360 and my O-320, timing marks where off a degree or two. This tool will get you spot on. I am told this isn't uncommon for the timing marks to be off. Not sure why, perhaps tolerance of journals, rods, pins, etc... can add up?
Even if your marks are good, parallax is taken out of the equation.
http://www.aircraftspruce.com/catalog/topages/timing_ind2.php?clickkey=4234

You can make your own with an old spark plug or purchase just the plug, and then use your smart phone clinometer.... and rubber band it to the prop.

Timing instructions for this indicator are on line.

http://www.aircraftspruce.com/catalog/topages/timing_ind1.php?clickkey=50844

A timing error of a degree or two makes no practical difference with a Lycoming, although it might be worthwhile to check the TDC mark once, early in ownership. To do it, all you need is a piston stop made by welding a post on an old spark plug, and pointer clamped to the case. Use the ring gear teeth to judge equality when the piston bumps the stop on each side of the TDC mark.

390 has a square boss on the left case half, upper front. Makes a good place to clamp a pointer. You can even drill and tap for a mount.