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If you’re like us, you’re shocked at the realization it’s been twenty years since the first Dodge Vipers hit the streets and race tracks of the world in 1992. With its all-aluminum V-10 engine cranking out 400 horsepower and – finally – rear wheel drive, the ‘92 Viper RT/10 breathed new life and excitement into Chrysler Corporation and established itself as a true world class performer.
While the Viper’s 488 cubic inch V-10 (505 cubes from 2003-on) has proven itself to be totally reliable under most conditions, professional road racers uncovered a weakness involving cam bore galling in 24 hour endurance races. Unlike many aluminum block engine designs, the Dodge Viper V-10 doesn’t use cam bearing inserts. Instead, the camshaft bears directly on cam bores that are precisely machined right into the parent material of the lightweight alloy block.
Interestingly, Chrysler used a similar approach within the aluminum block Slant Sixes of the early sixties – as did AMC with its die-cast inline six of the same time frame (see this month’s Steve Mags Speaks for more on this topic). Again, the direct-acting cam bores work fine under normal high performance use and are even standard fare in Top Fuel Hemi blocks today.
Things get iffy during endurance race events where the engines are run at peak output for 24 hours. Here, some Viper road racers have noted a tendency for the cam bores to gall and wear out under the incredible strain. Once this happens, the $5000 block becomes an anchor. Or does it?
Click to enlarge »Thanks to a novel repair technique conjured by Gene Ohly and Jaime Gonzalez at Evans Speed Equipment, salvation comes in the form of some specialized machine work and the use of AMC 401 cam bearing inserts. Let’s watch as the guys save an otherwise usable Viper engine block from the recycling bin.
The pointer indicates light wear on the number one cam bore. Though photography is impossible without slicing into the block, the extent of bore damage is increasingly severe on the number two, three, four, and five bores. In fact, the number three and four bores exhibit metal displacement and pitting you can feel with your finger. At the other end of the block, the number six bore is only lightly scored.