Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Vacuum Switch
With the cap of the leading ignition distributor removed, remove vacuum sensing tube from the vacuum advance tube of the distributor and attach a vacuum gauge in its place. Proceed as follows:
- Hold mouth to tube of vacuum gauge and suck in. Watch vacuum gauge and listen for the vacuum switch to change from ON to OFF at approximately 7.09 in. (180 mm) Hg. Vacuum switch should then change from OFF to ON when vacuum is reduced to approximately 4.72 in. (120 mm) Hg.
- Replace distributor cap and replace vacuum sensing tube to the vacuum advance of the distributor. Remove thermosensor connector and connect timing light to the high tension lead of the trailing distributor.
- Run engine at idle speed and then raise RPM. Timing light should stop flashing when speed is raised to between 1600-4200 RPM.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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