Engine Valve Spring Check Spring

What Is an Engine Valve Spring Check Spring?

An engine valve spring check spring — often called a checking spring or low-tension checking spring — is a specialized engine service tool used during engine assembly and tuning. Unlike production valve springs, these low-tension springs are designed to be installed by hand in place of standard valve springs, holding components in place with just enough force to keep everything aligned without the full resistance of a performance spring.

Whether you're checking piston-to-valve clearance, rocker ratio, valve lift, degreeing a cam, or measuring for pushrod length, checking springs are a necessity. By substituting a light checking spring for the stiff production unit, engine builders can rotate the engine by hand and take precise measurements without fighting heavy spring pressure — reducing the risk of error and saving significant time during assembly.

Why Valve Spring Checking Matters

Valve springs are one of the most critical and most overlooked components in your engine. Proper selection of the valve spring begins with identifying the application and selecting all of the valve train components to achieve the engine builders' goals. The spring must be matched with the entire valve train in order for the engine to reach its full potential.

Almost all engines use valve springs to close the intake and exhaust valve during combustion cycles. The cam, pushrods, lifters, and rocker arms do all the work of opening those valves, but it is the spring that closes and keeps the valve closed during engine operation. Given how critical this relationship is, verifying clearances before final assembly — using a dedicated check spring — is a fundamental best practice for any serious engine build.

Once valve springs have been installed, it is important to check for coil bind — meaning when the valve is fully open, there must be a minimum of .060" clearance between the coils of both the inner and outer springs. If this clearance does not exist, you must change either the retainer or the valve to gain more installed height, or change to a spring that will handle more lift. Check springs make this verification process far easier and more accurate.

What to Look for When Shopping Check Springs

• Free length: Match the check spring's free length to the approximate installed height range of your production springs so it seats properly in the spring pocket.
• Tension level: Low-tension designs allow hand-rotation of the engine for clearance checks without stressing components.
• Diameter compatibility: Confirm the outside and inside diameter of the springs that need to be tested, then verify the pressure of the springs that the tool will need to accommodate.
• Application: Check springs are used for piston-to-valve clearance, pushrod length measurement, cam degreeing, rocker ratio verification, and valve lift checks.

Top Brands for Engine Valve Spring Check Springs

COMP Cams is the benchmark name in valve train technology. Their low-tension checking springs can be installed by hand in place of valve springs, simplifying measurement of piston-to-valve clearance, rocker ratio, cam degreeing, and more. With decades of racing and performance engine expertise behind every product, COMP Cams check springs are a go-to for engine builders at every level.