It really doesn't matter where the rotor is for timing. You must understand that the poles of the distributer cap are only 45 degrees apart. When the secondary voltage potential rises it takes the shortest path to ground; normally through the rotor across the gap into the plug wire and finally across the plug gap to ground.

If as you say the fire is coming to the rotor when it is 40 degrees off it will thus only be 5 degrees from the next pole. The previous firing was actually number one by that account.

I don't think that when the trigger points fire, makes much difference. The Jag V12 of the same era fired six injectors at a time; timing of injection isn't of much consequence at the mixtures those cars ran at. Besides what applies to one cylinder applies to all. The important point is that fire went through the number one plug wire at the proper time and the rest follow in proper order.

I will say that I haven't set a D-jet MB to factory timing specs in atleast 30 years. I would jump that timing atleast 5 degrees maybe ten. Another point is that many 5ATDC settings are really wrong because that factory setting was based on a good, functioning vacuum retard being hooked up and operating. I always check the timing with all the lines disconnected first and then replace the vacuum retard line and see what happens. The timing should jump 10 degrees at least when the vacuum is removed. Thus I look for 15 degrees BTDC with the vacuum line off to add 5 DEGREES to the factory setting.

That fuel system does much better with some manifold vacuum. I try and get 17in at idle through timing and mixture control.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician