In 1997 former President Clinton began his second term, scientists cloned Dolly the sheep, the spacecraft Pathfinder landed on Mars, and the Spice Girls released Spiceworld-their second Number One album-making the group the first British band since The Beatles to have two albums on the U.S. charts at the same time. Rock aficionados around the world mourned. That year, I was in the Bay Area, taking pictures and scribbling notes for an engine story that would appear in the August 1997 issue of Hot Rod magazine. Mike Blackstone was caressing a big-block Chevy to pump out what was some serious pump-gas horsepower for the day. Fastest street car racing was starting to get crazy and people were losing sight of the street aspect of fun, go-fast cars. This 557ci engine coming together in Blackstone's shop was designed for
both street and dragstrip duty.
After years of abuse on the...
After years of abuse on the street, this race-bred big-block Chevy developed a nasty valvetrain noise and demanded some attention. At Kurt Urban Performance, the top end of the engine was disassembled so the whole valvetrain could be inspected. This engine was built to perform really well on the dragstrip and be tolerated on the street. As such, the valvetrain required more maintenance and simply didn't last as long as a more docile setup would have.
Nearly 15 years later, the engine has seen more than a dozen dyno pulls topping out at 893 hp and 740 lb-ft of torque, countless trips down the strip with and without nitrous, and thousands of street miles, including a drive from Los Angeles to Detroit. The concessions made in favor of more power in this big brute eventually created durability issues. First, we lost a lifter driving the car through Chicago. We tossed in a new set of lifters, changed the oil, and kept driving. Within a year, though, a mystery valvetrain noise developed.
We do need to explain something about this specific engine that drove the original and the replacement valvetrain components. This was never about building a docile street engine that will deliver 50,000 miles of service by just changing the oil and spark plugs. It's not about a smooth idle or having vacuum to operate power brakes. This is about big, nasty power that scares Toyota Prius drivers when we pass them in the HOV lane. Even in our quest to replace key pieces of the valvetrain, we wanted to maintain as much of the power as possible. Our true interest was to only make compromises required for higher durability on the street. Make no mistake, these are still race-inspired designs, but thanks to nearly 15 years of technical advancements, this valvetrain should require less maintenance and deliver better endurance on the street than the
previous generation.
We recently took the engine to Kurt Urban Performance to tear it down and rebuild it. Urban normally builds LS engines these days, but in the early days of fastest street car racing, he built hundreds of big-block Chevys. He was very familiar with the parts we had in this engine and what the engine was built to do. We worked with COMP Cams to update the old valvetrain and solve some of the age-old problems with running a radical cam profile on the street. Quite a bit of new technology has developed for demanding applications like this. Even though this engine is on the radical side for the street, nearly all of the components are identical in function to any big-block Chevy,
and the technology is similar for any cam-in-block engine. So if you have one of these old faithful engines in your street car, there's most likely a new trick for it in this article.
The first step in any engine...
The first step in any engine upgrade should start with a thorough inspection of wear to determine what needs replacing. The mystery noise in our big-block Chevy was a damaged valve tip (arrow). The wear pattern on the other valve tips showed us that the valvetrain geometry was good. This failure was simply a matter of too many street miles on components that were engineered for racing.
This engine was built with...
This engine was built with titanium intake and exhaust valves. These are ultralightweight for high revving, and they require a little less spring pressure than a heavier stainless steel valve, however, they aren't meant for prolonged street use. Valvespring and cam profile technology has evolved so much that the 7,000 rpm that this engine spins to isn't a problem with heavier valves that will wear better on the street.
The solid roller lifters used...
The solid roller lifters used in this engine were standard race components. With this type of hardware, durability is measured in run hours. You can get quite a few trips down the dragstrip or even on a circle track compared to the run time involved in driving across the country. And most race engines get freshened up each year, which isn't necessarily true with a street engine