If you hear telltale signs of the timing of your car not being quite right, such as pinging, backfiring, or if the car runs too rich or too lean, you will need to either take it to a mechanic or adjust the timing yourself.
When the piston comes up during the compression stroke, just before the piston gets to the top of its compression stroke (which is called “top dead center”), the spark plug should fire. Over time, this tends to get misaligned somewhat, resulting in a less-than-optimum spark plug firing time. The distance before the “top dead” center is the ignition timing, and it’s represented by a row of graded numbers on the balancer or flywheel through an access hole. [3] X Research source
Numbers to the left of zero on the timing tape refer to the piston as it travels down, while numbers to the right of zero refer to the piston’s upward motion. Moving the wheel right is called “advancing” the timing, while moving the wheel left is “moving back” the timing.
The “gun” works by illuminating the timing marks in a strobe fashion as it spins, allowing you to see the point at which the spark plug is firing on the timing index. When the spark plug fires, the sensor sends a signal to the light, which strobes in the gun, illuminating the numbers at the proper moment.
As the RPMs increase, the point at which the spark plug is firing should also increase somewhat. This is normal, because ignition works on a curve, allowing for the speed increase and adjusting the timing accordingly. To check for total timing, you want to be sure to rev the engine to at least 3500 RPMs. This will allow you to make sure the curve of the ignition timing is being set, as well as the initial timing.
Vacuum timing works by making minor adjustments at at low RPM by rotating slightly to adjust for the timing.
If you don’t know your timing number, talk to a licensed mechanic or employee at your local auto parts store to consult their manuals and find the proper timing number.
If the rotor turns clockwise, you’ll advance the timing by rotating the distributor counterclockwise, and vice versa. It’ll take some touch to get it right, so it helps to have someone to rev the engine, check the number, and twist the distributor.
Total timing minus your base timing number should meet your engine specification for total advance degrees. If the number is not as specified then you may have a distributor mechanical advance problem.
