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.
Dual Diaphragm Distributor: Operation
The outer diaphragm is coupled to the movable breaker plate. An increase in vacuum pressure moves the diaphragm against advance diaphragm spring tension, causing the movable breaker plate to pivot opposite to distributor rotation. Thus ignition timing is advanced, and this is to occur during normal road-load operation, but not during deceleration or idle. When intake manifold vacuum is applied to inner diaphragm (retard) it moves inward toward the distributor. This allows the advance diaphragm to move, causing the movable breaker plate to pivot in the same direction as distributor rotation. This retard of ignition timing automatically occurs during engine idle or deceleration.
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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