Thursday, February 7, 2013

Clearing the myth of Ignition Advance Angle on the 8v M102 engines

For all the (pre-91 non-cat) 8v M102 engine owners,
(this includes the 200e, 230e and some variants of the 190e)
when was the last time you had your ignition advance angle checked?

There were some myths of setting it to a certain angle in order for optimized performance..

And as the M102 engine ignition angle/timing adjustment has to be done manually with a timing light, the process is quite tedious and no workshops seems to have a good answer of what is the best timing to adjust it to based on the current octane level of petrol versus the grade of petrol's octane level available back then.

By looking at the close up picture of the trigger wheel, one will understand that it is impossible to attain 13 degrees or 18 degrees.

The original makers of this engine set a notch in order to aid the adjustment of the ignition timing/angle close to 15.

The deviation markings were in 5 degrees and with the compact layout of the components in the way of the timing light shining on the trigger wheel, it is almost impossible to get it correct at any other angle than the specified one with the notch key that gave a better visual indicator.

So next time, if a mechanic informs you that your ride is set to an ignition timing/angle of 13 or 18 degrees, you might want to ask him how he is able to be so finite about the number and perhaps show him this article and picture.

Only 5 degrees deviation on the trigger wheel