Timing Control Systems
- Connect timing light to vehicle. Start engine. Disconnect vacuum hose from vacuum advance unit. Increase engine speed while monitoring timing marks with timing light. Timing should advance. If timing does not advance, inspect distributor advance weight mechanism for binding.
- Connect a hand-held vacuum pump to vacuum advance diaphragm. Slowly apply vacuum to diaphragm while monitoring timing with timing light. Timing should advance as vacuum is applied. If timing does not advance, check for diaphragm-to-distributor plate linkage binding. If linkage moves freely, replace diaphragm.