• Holley 4000 Spark Control

    Holley 4000 Holley 4000 Instruction Sheets Holley 4000 Visual Instruction Manual Holley 4000 1955 Newsletter What Does The Spark Control ValveĀ Do? The spark control valve in the passage from the throttle bore provides an efficient degree of spark advance during periods of acceleration by momentarily providing a partially retarded spark….