By David Reher, Reher-Morrison Racing Engines
“There are some basic skills that must be mastered to build an engine successfully.”
I traveled backward in time last week. It happened while we were rebuilding a big-block Chevrolet engine. This particular engine won the 1982 NHRA Pro Stock championship, and overhauling it was like firing up a time machine.
We’re creating a replica of the championship-winning Reher-Morrison Camaro that will be displayed in the Hendrick Motorsports museum in Concord, N.C. I consider it an honor to have one of our race cars alongside Rick Hendrick’s stable of NASCAR champions. We’re out front with the fact that it’s not the real car – the original is under the care of a collector in West Texas – but the motor is the real deal.
In its time, this was the baddest big-block Chevy in the country. Today there are better parts and more advanced technology in just about any bracket racing engine we build at Reher-Morrison.
I’m looking at this killer engine from 1982, and shaking my head. The genuine GM aluminum cylinder heads still have “X” marks on the castings that signify they were made with cores we’d shaved at the Winters foundry. It’s got stock-diameter lifters, without a lifter bushing in sight. Aluminum rods as big as clubs, stud-mounted rocker arms, and spindly pushrods – that was the state of the art 28 years ago.
Seeing an artifact like that 1982 Pro Stock engine reinforces my belief that we are currently living in the Golden Age of engine development. Many of today’s off-the-shelf parts are superior to the handmade, high-dollar, top-secret components that powered yesterday’s record-setting Pro Stocks. In fact, I sometimes fantasize about racing one of our Super Series sportsman engines back in the day when the Reher-Morrison Chevrolets were battling Glidden, Johnson, and Iaconio for the top spot in Pro Stock. I think it would have been a powerful weapon.
My intention is not to wallow in nostalgia, but to point out the strides in materials and technology made by aftermarket manufacturers. There is a multitude of aftermarket blocks available in a variety of configurations. If a customer wants a block with a 55mm cam, I can order one from the manufacturer instead of boring out the cam tunnel on a mill in our shop. If a racer wants cylinder heads with a 14-degree valve angle, I can get them with a phone call instead of spending days building up the decks with aluminum welding rod. Life is definitely good for racers and engine builders these days.
Unfortunately the law of unintended consequences hasn’t been repealed, and there is a downside to this rich bounty of parts. As always, the devil is in the details. With so many manufacturers producing so many variations, finding compatible parts can be extremely difficult for do-it-yourself engine builders. Just consider the myriad differences among “conventional” big-block Chevy cylinder heads in valve diameters, valve angles, guide locations, and combustion chamber shapes. A piston dome that fits one head perfectly can be a total disaster with another head. The height of the valve seats, the location and depth of the valve reliefs, the profile of the dome, the lift and duration of the camshaft, the rocker arm ratio, and a dozen other design features all must be considered.
I’m told that GM has produced more than 95 million small-block V-8 engines. Replacement parts are available from any well-stocked dealership or auto parts store, and there is a reasonable expectation that every part will fit every engine. The market for specialized racing components is tiny in comparison, with no standardization among the various aftermarket manufacturers. Every manufacturer has a notion about how to make better parts – that’s what drives the performance industry. With this continuous development, it’s up to the engine builder to make sure that the parts will work together.
Building an engine is an enjoyable and rewarding experience for many racers. That’s how I got started in racing, and I’m grateful that eventually it became my livelihood. But for some people, engine building is an exercise in frustration.
I believe there are some basic skills that must be mastered to build an engine successfully. These include the ability to degree a camshaft, check piston-to-valve clearance, locate valve notches, measure valve angles, verify dome-to-head clearance, and align the intake manifold runners. There is no lack of information on these topics: Books and videos are available that describe these procedures in detail, and several schools teach the fundamentals of building racing engines.
High-tech parts can be enticing, but a successful engine builder doesn’t overlook the basics. For example, when you’re building for maximum power, compression ratio matters. Piston-to-valve clearance is a major factor in determining compression ratio because the valve pockets are typically the largest surfaces on the piston dome. If the valve reliefs are deeper than necessary, it’s easy to give up 10cc or more of dome volume. That can mean the difference between a 15:1 compression ratio and a 13:1 compression ratio – and two full points of compression will have a huge impact on performance.
What good is a set of the latest high-dollar CNC-ported cylinder heads if the compression ratio is under par? Few racers have the equipment and expertise to test cylinder heads, but anyone can check the compression ratio with a burette and a piece of Plexiglas. It’s a basic skill of engine building.
I’m continually amazed at the subtleties of engine building. Just changing from one brand of lifters to another brand can change the engine’s oil pressure by eight or 10 psi. How is this possible? Take a close look at the oil grooves in the lifters. An annular groove acts like a restrictor to reduce flow through the oil gallery; a straight hole allows more oil to move through the lifter body and consequently reduces oil pressure. An inexperienced engine builder would be looking at the oil pump to fix a problem that’s really caused by a difference in lifter designs. That’s just one example of the complexities of a racing engine that’s assembled with parts from dozens of suppliers.
Looking at the parts and pieces from that 1982 Pro Stock engine, it’s apparent that we didn’t know what we didn’t know. If we had understood the importance of valvetrain dynamics, the performance benefits of lightweight parts, and the impact of combustion chamber design, our engine would have been much different. We simply didn’t have the parts and the knowledge to build a more powerful engine; we did the best we could with what we had to work with.
The evolution of engine technology never stops. I’m sure that 30 years from now, some builder will tear down a 2010 Pro Stock engine and wonder, “What were they thinking?”