Before timing the ignition, you need numbers. These numbers can be acquired through aftermarket repair manuals, manufacturer repair manuals, and reputable Internet sources, and from the car's emission labels. Before even picking up a tool, know what RPM the engine is timed at, the degrees before top dead center range and which engine cylinder is cylinder No. 1.
The vast majority of engines time the engine off cylinder No. 1. If a manual is short on information about the key cylinder, follow these general rules:
- Four- or 6-cylinder engines. On most in-line 4- and 6-cylinder engines, cylinder No. 1 is the most forward cylinder.
- V-6 or V-8 engines. Most V-type engines use the left front cylinder at cylinder No. 1.
- Transverse engines. Most front-wheel drive vehicles with transverse engines use the far right cylinder as cylinder No. 1.
There are exceptions to this rule. Ford V-6 and V-8 engines, for example, use the far right cylinder as cylinder No. 1. In-line 6-cylinder engines produced by Jaguar before 1988 are timed from cylinder No. 6. It pays to do your research first.
You now have your numbers in hand, you know where cylinder No. 1 is and you know what RPM the engine should run at during timing. Here are a few more things to check, and then check again:
- The engine should be at normal operating temperature. This means the radiator hose leading from the engine to the radiator should be hot and pressurized.
- If the engine is equipped with a vacuum-advanced distributor, remove all vacuum hoses and plug the one into the distributor.
- If the timing advance and retard control to the distributor is computer-controlled, you'll need to disconnect the "set timing" connector wire, ground a diagnostic terminal or disconnect a control connector. The timing instructions will give you the specifics.