Comp's aluminum roller rockers provided the best dyno numbers. They were a good match for our dyno mule's peak power and rpm ranges.
During the dyno session, NTI students regularly checked the spring pressures for consistency, and they held true.
The Hi-Tech rockers are designed for high stress environments. They performed flawlessly, but our dyno mule may not have been aggressive enough to really put them to the test. These rockers are probably better suited to a race engine with more power and a higher rpm range.
Comp's shaft-mount rocker system is a premium piece of equipment. The peak torque and horsepower numbers were down from the aluminum rockers, but the shaft-mount system showed an interesting characteristic. After peak power, the horsepower did not drop nearly as quickly with the shaft rockers as it did with the aluminum rocker set. This tells us that the shaft-mount system is better at keeping the valves under control as the rpm increase. The system is expensive, but it is probably your best bet in high-rpm applications where maintaining valve control becomes increasingly difficult.
Here's a problem that's confronting more and more Chevy racers. The stronger beehive valvesprings we used have a wider base than the stock springs. This means the gap between the two exhaust valvesprings in the center of the head is too small to fasten the head bolt. Those springs must be removed before the head is bolted down, and then they must be reinstalled. CV Products sells the perfect valvespring compressor for this job. It works with the head on the engine and can even be used with the engine in the race car if you need to make a spring change at the track.