Many questions arise when Blocking Off a Power Valve. Power valves are used for off idle /transition enrichment. They are an efficient way to enrich a motor when it needs it without having to over jet it.

If you are running a high performance motor that goes from idle to wide open throttle and that’s all it does and you want to block off the power valve you may need to enlarge the main jet 6-8 sizes.

For example, a 4bbl carb with a primary power valve and a 72 jet would require an 78-80 jet if you were to remove and block off a power valve. And the same would apply if there was a power valve on the secondary side.

Simply unscrew your power valve and using our part number pv25620, thread the block off plug in using the new gasket that comes with it. Make sure that when you thread the plug in that the gasket seats properly on the block off plug.

Do not forget to change the main jet to accommodate the change that you just made. Our part number for main jets is mj2240 then select the size that you need.