Reality Racing - Inside Robert Yates Racing Engine Shop

"We went over the top on this engine to run 24 hours...," John says, "[later] we'll be bringing the level of parts down to meet the realities."

Head gaskets are multilayer, stainless-steel-shim-style from Cometic. With these, John is trying something new as a guinea pig for the Winston Cup engine shop. He says the sports-car racing makes a great 24-hour durability test, and he's found the Cometic gasket's beading works quite well.

Another place the stock engine works great but is nevertheless highly modified is oiling. To lower the engine in the chassis for an improved center of gravity (the crankshaft centerline is only 43/4 inches above the pavement), reduce windage and thus increase horsepower, and provide significantly more oil capacity to reduce the number of trips each oil molecule makes through the engine in 24 hours, a dry-sump system replaces the stock wet-sump design. Aside from simply removing the stock oil pump, all the changes are either in the oil pan or externally in the RYR pump, lines, tanks, and so on. In other words, the internal oil passages are left stock, and oil flow to the top of the engine is not restricted "We're not that smart yet," John says.

Initially, the timing chains gave John fits--he was melting chain guides. The cure is what he's using now, stock chains from manual-transmission Cobra engines. Yes, there are automatic- and standard-transmission chains, something John didn't know until a few days before the 24-hour Daytona race. He was getting donor parts from all sorts of sources at FoMoCo--some from Marauders, some from regular Cobra engines, and probably even the odd Navigator piece. It turns out the Cobra chain is polished on the backside where it rubs against the guides and tensioners so it doesn't wear them out at high rpm. The tensioners are the same in all engines, and the Yates engines use stone-stock tensioners.

The cam sprockets started off as modified stockers at the Daytona race, with John working on custom RYR sprockets for future engines. The only issue is cam adjustability--he needs a finely adjustable sprocket for precisely dialing in the cams.

So far, John has tried cams from Andy Schwartz's experimental pile, along with a Comp Cams grind. All the specifics are confidential, naturally. "Just call it a 12.5mm cam," says John, who went on to say there was nothing too radical and the result was a huge, flat torque curve.

As are the chains, much of the rest of the valvetrain is stock, including the finger followers and hydraulic lash adjusters. The girdled cam bearing caps have to be modified for clearance with the large lobes. "Nothing a hacksaw won't take care of," John says.