Check the listing for details. HOLLEY POWER VALVE SAVER KIT, AED BG DEMON GRANT QFT CARBURETORS. Condition: New. Listed at 8.95 USD. Millions of production Holley performance carburetors had no provision to protect the power valve in case of an engine backfire. Repeated engine backfires or engine after run can cause damage to the power valve diaphragm and cause a rough idle and rich condition. This new top quality OEM Holley power valve saver kit is the answer! A must have on Holley and other similar carburetors that do not have a power valve saver from the factory. This kit comes with the seat washer, spring, check ball, and retention washer. NOTE: you will need to purchase the proper drill bit (#16 drill bit available at most automotive or hardware stores) for installation. You will need to drill the power valve port in the baseplate to a depth of .375" Please see our store listings for a complete selection of high performance parts for Holley carbs.