Z Tech Tips Offset Timing Mark
Most references for total timing advance is 34° to 37° at 3,500rpm.
The problem with setting this is that the timing marks on most Z's only go to 20° or 30°
There are three ways to tune the car and measure total advance at 3500rpm
- Buy a higher degreed damper pulley.
- Use an expensive timing light with advance/retard feature.
- Scribe an offset mark on your damper pulley
This tech tip is for #3.
This is a prime sample of Atlantic Ocean environmental effects. (I smashed the rim with a hammer after removing as the way the brittle metal snapped amazed me. It was like a ceramic).
This beast is from an 80+/-1year ZX that spent some time out doors.
The timing scale only goes to 30° so measuring 34°-37° would require guessing. It is worse on earlier Z's as they only show up to 20°.
Note the corroded timing scale ~ 0°. I cleaned it up for the pics but the metal is totally missing!!! It is a secret East Coast way of lightening cars without breaking any racing rules. Maybe one day I'll go over saltwater porting.
Back to business. Here is the timing tick on the pulley rim lined up at the 0° point. When you set the engine to top dead center (TDC) it should be like this.
Here is the timing tick when set to 10° advance. This is a typical idle timing for most Z's (consult your FSM for your particular model when tuning)
A divider can be used to measure 10°. You can choose any number really. If your mind was set on having 35° of total advance then 5° or 15° would be a nice width (arc to be precise).
Transfer the 10° arc to the damper pulley rim and file or paint a second tick
Here is the second "+10° tick lined up with the 24° point on the scale. This would be a 34° total advance.
If you feel spanky, use some paint or your wife's/girlfriend's/mom's nail polish to highlight the timing ticks.
Use different colours to distinguish the stock and +10° offset ticks. Make sure they match your hair and dress.
Finally, if you ever wondered why it was called a damper pulley, the rubber ring connecting the inner and outer parts should explain.
This rubber dampens crank vibrations to minimize bearing wear however, it is a weak point and the two parts can separate. This then dampens your spirits.
As well, the notch in the wheel where the woodruff pins go can wear out and cause timing problem. This problem is especially bad when the lower timing chain sprocket's notch wears.