For lots of people this is still the most popular engine on the market. S&S starts with their bullet proof crankcases, flywheels, cylinders, and heads that they have offered for years, and finish the engine with new premium valve train components. Billet tappet guides, and rocker boxes look outstanding, and offer the kind of performance you have come to expect from S&S. What you can't see inside the engine is just as impressive. The new Shovelhead style tappet guides are designed around the quiet, dependable Evolution style tappets. Corrected tappet guide bore geometry assures correct valve timing using Evolution style cams. The unique adjustable pushrods are collapsible for easy removal and installation, but are stronger than the old style adjustable pushrods. Inside the billet rocker covers are S&S's exclusive straight rocker shafts and the new S&S forged Shovelhead style roller rocker arms. The result is a Shovelhead engine that has the classic stock appearance, the increased performance and the modern technology, which makes them ideal for those who find engine life more important than performance. For lighter bikes in performance applications there is also a High Compression version with dual plugged heads available. Alternator style engines come with natural cast aluminum, or billet aluminum nose cone covers as specified below. Engines are assembled by S&S technicians, and come, except for the 80CI version, with an S&S Single Fire Super Stock ignition, carburetor and air cleaner. The S&S Single Fire Super Stock requires a single fire Ignition coil that must be ordered separately. SH Series engines feature a 2 year limited warranty.