The Quick-Lift design actually increases the rocker ratio at the start and end of the valve opening cycle. The mid-cycle ratio is the stated ratio. The rocker ratio is increased by utilizing basic geometry and arranging the position of the contact points for the valve and the pushrod through the cam cycle so that the NRR may start out higher by + 0.20.

This means that a rocker that reached a NRR of 1.50 at maximum valve lift may start out around 1.70 and end with the valve closing at 1.70. The advantage of this is the air/fuel mixture gets a better start entering the chamber, allowing better flow characteristics and increased total volume that is available for combustion. In short, this adds up to more horsepower.

Extensive testing and redesign has yielded an improved design that shows an increase in horsepower as well as the ability to endure. Anytime we can raise the power output while maintaining endurance, we have moved ahead in the performance game.

A New Bearing Design The benefits don't stop with material and geometry improvements. The new rocker arm has an all-new bearing design that has been perfected and proven in competition. It is technically a surface "friction" bearing, but that term does not do it justice. What this new bearing design does is reduce friction and wear over the common needle or roller bearing design.

Truthfully, it took a lot of R&D to find just the right combination of materials and refine the process of manufacturing these bearings, but the product has proven itself. The design of these bearings for this application just makes sense.

The high pressures and unique motion of the rocker arm necessitates a design that can deal with those functions. The new PMC bearings provide increased surface area to spread the loads produced by stiff competition valvesprings while maintaining a layer of lubricating oil at all times to keep friction to a minimum. Less friction and more lubricating oil means less wear and tear.

A needle bearing exerts a lot of localized load on the bearing race and rocker shaft surface, creating heat. The bearing also acts as a squeegee and wipes most of the oil off the mating surfaces. It has to. In contrast to this tendency, the new PMC bearings spread the load over a large surface, and there is nothing to wipe the oil off the surfaces.

A layer of oil always remains between the bearing and the mating surfaces to lubricate and cool the components. This means that these new rockers can withstand higher open than ever before without failure.

The shaft size is larger, too, due to the fact the design does not need roller or needle bearings. The shaft in the new design is 51/48-inch in diameter. This provides even more bearing surface for reduced load per unit of area and less friction.

One More Thing To complete the redesign, another key change was made that deviates from some previous designs. The angle of the valve lash adjuster to the pushrod was changed so that when the valve is at full lift, the valvespring is at full compression; the spring pressures are the greatest; the pushrod is inline with the adjuster; and the pocket is perfectly matched with the end of the pushrod.

This may not sound like a big deal, but it is definitely an improvement. Lateral loading of the adjuster screw can alter the hole shape, and the adjuster can then become loose. Since most of the load is at high lift, it does no good to be inline while the valve is at rest and then misaligned at full lift. Oiling is improved, too, when it is most needed, and that is when the system is under full load.

Looking at all of the changes and why they were made, one top engineer who teaches the art of high-performance engine building remarked that he had finally seen a rocker arm that was designed correctly. We think this new rocker arm design will change the way engine builders value a rocker arm geometry that improves basic flow through the engine. The secret is out for those who were previously aware, and soon everyone will want to take advantage of these unique advances.

SOURCE
Crane Cams
530 Fentress Blvd.
Daytona Beach
FL  32114
3-86/-252-1151
N/A
www.cranecams.com