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.
Cold Lock-Out Spark System: Operation
When engine coolant is below 128°F, PVS is closed and manifold vacuum passes through the restrictor to the distributor vacuum advance. When heavy acceleration is applied, manifold vacuum is bled off slowly through the restrictor. This avoids a sudden ignition timing retard on cold engine acceleration. When engine coolant temperature is above 128°F, PVS opens allowing vacuum to flow unrestricted.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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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