[Phenius]

Heya guys. I'm new to engine tuning, so I was wondering if anyone knew of a site that would explain to me what the roller-rockers do exactly, and what 1.7 or 1.6 means. I know this may sound like a dumb question to most, but i'm a noob I just want to absorb all the info I can before I decide what to do to my car, and how. Thanks!

 

[Bogart]

Roller means that the tip of the rocker that contacts the valve stem is a metal wheel that rides on needle bearings. It helps reduce frictional losses. Non-roller rockers are just a solid piece of metal.

1.6 and 1.7 refer to the rocker's ratio. For example, with a 1.7 rocker, for every 1mm the pushrod moves the one end of the rocker upward, the other end pushes the valve 1.7mm downward. By increasing the rocker ratio you can cause the valves to open wider.

One concern with high-ratio rockers is that they can wear out your valve guides quicker because of increased side-loading on the valve stem. Roller tips can help redice side-loading somewhat.

I hope my explanation made some sense to you. If not please forgive me, I'm half drunk as I write this. :tongue

 

[tmoss]

Here is a sight that does a great job of explaining the details of how rocker geometry works - just don't buy his product - take that as first hand advice (and that is all I'm going to say about that). The site is NOT easy to navigate, but have some pateince and poke around.

www.mid-lift.com

 

[Phenius]

hawesome, thanks guys

 

[jrod92]

Are roller rockers generally louder than non rollers? I seem to have alot of noise coming from mine.

 

[macx]

Roller rockers on a hydraulic cam should not have any appreciable noise.

If you do, either they're not adjusted properly (if stud rockers), shimmed right
(if pedestal rockers) or the pushrods aren't long enuf.

Check Crane & Comp Cams websites, they go into good detail on
rocker arm geometry and adjusting them.

They recommend .020 to .060 lifter preload. I held mine to
.030 to .050.