The grief I had with Jesel rocker arms is due to the offset on the intake valves in a 440-1 type head combined with a poor design for holding the intake rockers in place. Even with offset lifters the angle is enough to hammer the rocker arm over against the piece that it registers against. That piece is a little C clip on the rocker shaft that positions the rocker. It rides against the needle bearing cage in the rocker arm. The needle bearing cage wears on the C clip and actually thins them out over time and at some point they will break. The needle bearing cages get beaten up from the repeated impact every valve cycle and the edges crack, deform and then the needles inside the bearings seize and gall the shafts. If you don't catch it soon enough the bearings will come apart and the little needle bearing rollers will fall into the motor and find their way to the oil pump, seize it up and shear off the tip of your bronze gear distributor/pump drive shaft. And then you are waiting on the right size engine bearings to put your motor back together! I hope my -.001 rod bearings get hear tomorrow! Oh, forgot about the oil pump and expensive oil pump cover that also got destroyed.

The end result of all this is over $1200 in repairs to just the rockers alone, and finally engineering a system for holding the rockers in place that doesn't rely on either the bearing cages or a C clip. So choose wisely, and hope you get many runs out of what ever you build