Why Use Roller Rockers:Roller rockers have a roller bearinged tip and trunion.
They are available in either bolt on non adjustable(Holden 173/202/253/308),bolt on adjustable for the same motors,and adjustable for most other motors(and the 173/202/253/308 if the heads are machined to suit)
The conventional rocker(pressed steel) pushes the valve to the guide as well as down. SICKHG on Mon, 20/04/2009 - 14:30. They are posi-locs they allow you to be able to adjust your rockers then lock them up with the allen key in the top. seems wierd someone would put them on std rockers though, they normally come with rollers. Cheers
Origin of the Name:
The roller rockers tip rolls on the valve head,almost eliminating valve guide wear.
Another advantage is strength. Rollers will handle heavy loads from Performance valve springs and sustained high RPM.
By rosco1 18/10/07@01:51When you fit a big(ish) cam to your motor, the higher it lifts, (meaning the valve opens more), can cause a higher side loading on the valve stem. A pressed steel rocker literally slides back and forth across the top of the valve stem, this friction transmits to side load between the valve stem and the valve guide. A roller rocker, by virtue of having a roller tip, allows the rocker tip to "roll" across the top of the valve stem, reducing the side load, and reduces the possibility of a valve picking up on a guide (grabbing).
If this happens, bye bye pushrod and often the valve. Bronze guides will allow you to get away with a bit of friction, steel guides....forget it, say a 276 HYD with standard rockers will often grab, if steel guides are used. The cost of a set of rollers is offset by the cost of having to rebuild the heads if ya grab a guide. Regards,