Holley Single-Stage Power Valve Sizes 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10.5

• Single-stage power valve for Holley performance carburettors
• Available in multiple vacuum ratings from 2.5 to 10.5
• Restores correct power enrichment under load and wide-open throttle

Holley single-stage power valves are a critical component of the power enrichment circuit in Holley performance carburettors. They operate using engine vacuum to control when additional fuel is supplied to the main system. Under light throttle and cruise conditions, the valve remains closed. As engine load increases and vacuum drops, the valve opens to deliver extra fuel, preventing lean conditions, hesitation and bogging while ensuring smooth and responsive power delivery.

These single-stage power valves are available in a wide range of vacuum ratings, allowing precise tuning to suit your engine combination and driving style. Each valve includes a gasket and is designed to provide reliable operation across street, strip and performance applications.

Power Valve Selection Guide

One of the simplest ways to select the correct power valve is to measure manifold vacuum at idle with the transmission in gear for automatic vehicles. The recommended power valve rating is approximately half of this vacuum reading.

Example: If your engine produces 20 inches of manifold vacuum at idle, the appropriate power valve would be a 10.5.

Specifications

• Product: Holley Single-Stage Power Valve
• Design: Single-stage
• Vacuum Ratings Available: 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, 10.5
• Function: Power enrichment under load and full throttle
• Compatibility: Holley performance carburettors using single-stage power valves
• Gasket: Included

Inclusions

• 1 x Holley single-stage power valve (selected vacuum rating)
• Power valve gasket