i've been battleing a high rpm miss 5900, for a few years now. it started when i installed ARE stage 2 heads, comp cams 306 cam, and their R series lifter. to make a long story short, i just got off the phone with comp cams and they told me with the r lifters you need to set them to 0 lash. what i was doing was setting them till i could move the push rod up and down(is that 0 lash?) then added another 1/2 turn. am i doing something wrong here?

 

"Zero Lash" is when there is no up and down motion from the cam lobe to the valve, but also the hydraulic lifter isn't compressed at all. It's difficult to exactly get there.

Here's a technique you might try:

Tighten the rocker nut slowly while rotating the pushrod between your fingers. You'll reach a point where the push rod just stops turning. You might have to do this a number of times until you get a good feel for it. Now tighten the nut 1/6 of a turn. That's one flat on the hex. Lock it there. You shouldn't be able to spin the pushrod now.

Remember that turning the rocker nut will easily start to compress the inner part of the lifter, so find the o-point as closely as you can.

I've had this recommended by someone very close to the source, and have seen it work well.

Just a thought. If your "miss" goes away somewhere above 5900, in other words, it's just at one rpm, you might have a valve train resonance around 5900. If 0-lashing doesn't help you might have to change spring pressure. If it still does it after 0-lashing, ask Comp for more help.

My $.02

 

I've used 1/4 turn and 1/2 turn just fine. When you can't jiggle them up and down anymore, that is zero lash. What you are doing is going 1/2 turn past lash, which should be fine. I'd blame your miss on something else.

Any other ideas?

 

i'm almost positive it has to be something in the valve train... this miss started after i switch cams and heads.
i've already changed all the plugs/wires, ignition box, coil, opti...

 

It's something else.

I'm using 1/2 turn after 0 lash with the R lifters, and it's working fine. Pulls to 7000 rpm.


Mike