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.
Engine Overrun Conditions
During engine overrun, carburetor throttle by-pass valve supplies sufficient mixture for proper combustion. This additional air/fuel mixture provides enough power to reduce effect of engine braking. To help overcome this unwanted engine braking feature, ignition is retarded 12° (crankshaft) through action of second distributor vacuum unit. When engine overrun creases and intake manifold vacuum falls to 18" Hg (1970-71) or 17" Hg (1972-73), air entering calibrated air bleed allows throttle by-pass valve to close and distributor vacuum unit to return to normal closed positions.
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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