When are aftermarket rocker arms needed with a hydraulic cam?

[Kern Dog]

Is it an issue of lift?  What are the limits? I ran a Comp Cam XE285 HL with .545 lift with stock replacement rocker gear and all seemed okay.

[firefighter3931]

It really depends on the total lift and the lobe agressiveness of the cam grind. The XE285HL will work with stock rockers but it will work better with an adjustable rocker arm assembly. 

The stock rocker arms are typically 1.4:1 ratio so you will lose some lift. 



Ron

[Kern Dog]

Elsewhere I read about the adjustable aluminum rocker arm kit from Hughes engines. Nike looking kit and reasonably priced at $550.

[firefighter3931]

The Hughes rockers are descent from what i've heard and read....but i have no personal experience with them. 

I would feel comfortable running them with a flat tappet or hyd roller cam where spring pressures are modest. 

A solid roller would get a fully rollerized rocker like Harland Sharp or T&D 


Ron

[maxwellwedge]

Just be careful if you are running a stock valve cover. There are clearance issues with some of the rockers with the baffle plate. This happened to me with the Hughes - even though they claimed no clearance issues with stock valve covers. Fired up the engine and I thought the world was coming to an end!

[b5blue]

  Another factor is if your heads/valves are used. (Other than brand new parts.) Shaved/surfaced heads LOWER the rocker shaft and cut seated valves will have stems will sit higher, the result can be your too tight into the hyd. lifters adjustment range. Consider that higher lift cams achieve that higher lift by reducing the non lift radius. They can't actually be higher or they would not be able to pass through the cam bearings. (So the lifter sits lower "at rest".) Then there may be variance between finished installed height/adjustment range from different manufacturers of lifters. Then the head gaskets themselves are available in different thickness also.  All of this eats away at factory tolerances for optimum valvetrain geometry. Consider cut to fit pushrods if your settled in on your build or adjustable pushrods from Smith Brothers if you may be changing some things later.  You could find yourself needing cut to fit pushrods even with adjustable rockers depending on your own build!   

[Kern Dog]

Good point, B 5. I appreciate the suggestions.