Sold in sheets (PN 8985),...
Sold in sheets (PN 8985), MSD's timing tapes fit vibration dampers from 5.25-8 inches in diameter. Marked in one-degree increments, the Tapes allow precision timing settings using a standard timing light.
Timing is Everything
It's all in the timing, they say. Well, other adjustments also play a big role in how your motor runs, but firing the spark plugs at the correct time certainly helps performance. Most 'wheelers simply set the timing to factory specs, others adjust it until the motor performs its best. Either way you'll need a timing light, whether it's to find the factory setting or to record the best-performing amount of advance once you find it.
Timing lights pick up a signal from the first spark plug in the firing order (number one) and emit a very short burst of bright light when that cylinder fires. By aiming the timing light at the timing marks on the vibration damper (harmonic balancer) on the front of the crankshaft, the strobe effect of a timing light "freezes" the damper's movement, which allows reading the marks as if the engine was stopped.
This is Mac Tools' middle-of-the-line...
This is Mac Tools' middle-of-the-line TL500E timing light, sporting dial-back from 0-60 degrees BTDC. It works by connecting the battery clamps to 12 volts and clamping the inductive pickup over the number-one cylinder's plug wire. Pushing the ON button below the scale activates the strobe, and turning the dial until the TDC marks line up shows the amount of timing advance on the scale.
Here are two ways to make it easy to see when the spark plug actually fires in relation to the timing marks. Simplest is using the Mac Tools TL500E dial-back timing light. With the Mac advance timing light there's no need to try reading the small markings at the damper. Instead, turn the dial until the (usually) well defined Top Dead Center marks line up, then read the amount of advance on the timing light's scale. It's a quick and convenient method, and far safer than sticking your nose into the territory of moving fan blades and belts in an effort to see small and cruddy timing marks down by the engine's lower regions.
With a regular timing light those marks must be legible, and MSD sells timing tape that is both easy to read and marked all the way from 12 degrees After Top Dead Center to 62 degrees Before TDC. Attached to the damper, these self-adhesive timing tapes make it possible to set the timing with precision using just a regular timing light.