Hyd Roller Valve Adjustment
First posted on Crane's website on January 3, 2005:
Hydraulic Roller Lifter Adjustment Recommendation
With the increased popularity of hydraulic roller cams, our phone techs are getting more questions on proper adjustment of hydraulic roller valve trains. First, a hydraulic roller tappet weighs more than a hydraulic flat tappet due to the extra mass of the wheel, axle and support struts. This extra mass, as well as the quicker opening rates available to the roller cam design, requires the use of higher valve spring on-the-seat pressures and higher valve spring open pressures to control the increased inertia of the lifter.
Higher seat and open pressures can cause pushrods to bend; therefore, use the stiffest pushrods available to assure proper valve action. (This is a “speed secret” that we’ve seen proven in countless dyno tests. We prefer heavy-wall pushrods for just this reason!)
Finally, hydraulic roller tappets will perform best with at least one turn of preload on the lifter. This is different from flat-faced lifters which perform best at zero 0 to ½ turn of preload. Tests at Crane R&D have consistently shown best performance (for hydraulic roller cam valve trains) occurs with the preload set at 1 ¼ - 1 ½ turns down from zero lash. This adjustment will maximize power throughout the RPM range and increase the useable top end by 200 - 300 RPM. This preload setting has been confirmed on every engine family we have tested! Check the tutorial in the front of the new Crane Cams Valve Spring Catalog for spring pressure recommendations for various applications.
I found this today & set mine again to 1.5 turns. My rockers seem to make less noise & I verified oiling.
I have Lunati hyd roller cam, lifters, & beehive valve springs 170/360#