Prestolite Timing. Center Mark = 30 degrees? 50HP

[777funk]

I just checked timing with a light by jumping the shift interlock, moving the shift lever to full throttle (while cranking the engine), grounding the top plug and disabling the bottom CDI (disconnected).

First question, does the center mark on the flywheel = 30 BTDC?

I put a timing light on it and am getting about 3 or 4 degrees minus on the timing gauge sticker in reference to the center mark. This is engine off of course. So If that is the case, I guess I'm getting around 26 or 27 degrees BTDC? I have read that I should be at 28 with cranking speeds so is this close enough?

 

[Jiggz]

Can you post a pic of the center mark you are referring to?

 

[777funk]

Sure. I don't have a (good) picture of the marks on this side of the flywheel on my pc unfortunately. But I drew in what I'm referring to in time on the first picture and. And I have a picture of the flywheel in a random position but I think I can almost make out the center mark and two surrounding marks. I colored them in slightly in red to illustrate what I'm trying to so.

To give context on what engine ignition I have (Prestolite CDI) Pre-D model from 1987.

 

[Jiggz]

Because some of these old motors flywheel markings were actually on vinyl tape, most of the markings were long gone. So most mechanics did is to mark the flywheel permanently. Most do have three permanent scribes or at least two. One mark is the TDC, the 2nd mark is either 28/30/32 degree mark and a 3rd mark is either the 32 or 34 degree depending on HP and Model of the motor. For my 89-125 HP, there are three scribes, TDC, 30 and 34 and yes the vinyl tape marking is long gone. Why 3 marks, well in addition to the TDC, one timing mark is for the static and the other is for the dynamic timing. Static timing is almost always 2 degrees more than the dynamic to compensate for the slop.
In your case, you can always verify those markings starting with the TDC marking. There are numerous ways to re-establish the timing marks but the simplest but not necessarily the most accurate is just by simply counting the number of gear teeth in the flywheel and dividing 360 by these number of teeth. This will give you how many degree(s) each gear teeth makes.
From the TDC, count the number of gear teeth to make 32 degrees which is the set timing for your 50 HP motor. Remember, if you are facing the stationary timing mark on top of the motor head, this 32 degree mark should be on the left side of the TDC mark.