S&S, Shovel tappet guides for Evo tappets

66-84 Shovelhead (NU). With Evo tappets, Evo cam, S&S Quickee pushrods for easy install

Polished. Allows you to use the improved hydraulics of Evo tappets in a Shovel. When retro-fitting these billet aluminum tappet blocks to a Shovel engine you must use 86-99 Evolution Big Twin hydraulic lifters, an Evo style camshaft and S&S Quickee pushrods. If desired you can oil the top end through the pushrods (with 512497 Quickee pushrods), Evolution style, when using S&S Shovel roller rockers (512493). Note: An Evo cam will have about 9% reduction in valve lift due to the lower S&S Shovelhead rocker arm ratio (1.5), when compared to the stock Evo rocker arm ratio (1.625). The stock rocker arm ratio of Shovelhead rockers is 1.43. Note: Adjustable pushrods are required. Also required are 512511 pushrod retainers/clips/keepers when using 512494 Evo style tappet blocks for Shovel. Since these tappet blocks are longer a shorter retainer of 2.800" length is required for correct pushrod cover spring tension.