Why should engine RPM be accelerated periodically when making carburetor adjustments?

• A. To clear excess fuel from the carburetor ('clearing the engine')
• B. To increase manifold pressure
• C. To test the ignition system
• D. To reduce fuel consumption

Answer: (A)

When you adjust a carburetor, you want to purge any excess fuel that may be lingering in the carburetor circuits. Briefly accelerating the engine drives that extra fuel through the jets and passages, helping to prevent a rich condition or flooding as you recheck the mixture. This purge ensures the engine responds cleanly when you return to normal operation and confirms the mixture is correct across the RPM range. Raised RPM does momentarily increase manifold pressure, but that isn’t the purpose here; ignition system checks are separate, and accelerating during adjustments isn’t about reducing fuel consumption.