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.
High Altitude Compensation System: Operation
Altitude compensator mixes air into gasoline when it enters idle/low speed circuit and main metering circuit passages in carburetor. Metering of air bled into carburetor is accomplished by use of an aneroid valve bellows, which simultaneously moves 3 spring-loaded needle valves.
As altitude increases, atmospheric pressure will exert less force on bellows, causing bellows to expand and mechanically open needle valves. Fresh filtered air is supplied to needle valves from inboard side of air cleaner element.
One-way check valves (if equipped) are located in series in the primary and secondary main metering air lines near carburetor. These check valves will prevent any liquid fuel from entering the altitude compensator housing. Altitude compensator is attached to front of heater air intake duct. Fresh air inlet to compensator is connected at bottom of air cleaner housing.
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.