Over the course of its production life the engine received many internal upgrades, including roller lifters (1992), a five counterweight crankshaft (1995), a reinforced block (1995, 2002), and longer head bolts (1999) among other changes. In 1993 the flex fuel Vulcan received Ford's coil pack based Electronic Distributorless Ignition System (EDIS), which the gasoline fueled version received in 1996.
