I had put 1.6 Roller tips on but they started squeaking and I got tired of them (I had to grind the rocker body for it to fit, so I just didn't trust them anymore so I switched back to stock, no more problems. A couple thousand miles later, A rocker came loose on my way to lunch. I towed it back to my house from work and when I got home ( no time-it was on the pass side), re-adjusted them on that side (engine running method) to 1/2 turn for the time being, I think I was at 1/4 turn before. So now I read up and the factory says 3/4 to 1 full turn so I adjusted the drivers side to 3/4 and then the pass side and I just can't seem to get rid of one of them clanking. I must have done that side 3 or 4 times, I had heard so much tapping that I could no longer tell the difference between the loose rocker tap when setting that individual rocker's lash and the rest of the rockers. I guess and needed a break, it was getting too hot also.

So I've done this about 4 times before and it went fine each time, even though one of the times a rocker came loose later on. I don't get what I am doing wrong. Am I supposed to do them in any sort of sequence even though I am using the engine running method? Am I adding too much preload even on stock rockers, Does the driver's side effect the pass side? (lifters are stock too I am pretty sure, but I lost my build info). I don't know why they would use anything else in this build. My springs are cranes and are good up to .600 lift.

 

Check your pushrods, with the rockers coming loose it may be bending the pushrods.

 

Only one was loose, pushrod looked fine when I took it out for inspection. Clacking didn't start until a just now while I was trying to adjust both sides to 3/4 of a turn. I'm going to try re-doing it tomorrow at 1/2 turn but I am afraid they one will eventually come loose.

 

Is the adjusting nut actually backing off? Does the nut look to be sitting higher than the others?

Look for differences between the quiet ones and the noisey one. There's gotta be a reason.

My FSM says 1 full turn from zero lash +/- 1/4 turn is stock; meaning anything between 3/4 turn to one and 1/4 turn is within GM spec.

More preload reduces valvetrain noise, but many guys opt to go the other way which is exactly the opposite from what all my recent research says should be done. You can do a GOOGLE search to read up on it for yourself.

Here's what Crane says:


Lifter preload settings of .004-.010? have been recommended for years (by many aftermarket cam companies including Crane) for maximum effort applications with flat tappet hydraulic valvetrains, but extensive testing at Crane Cams R&D Department has proven conclusively that hydraulic roller lifter valvetrains operate best with .050-.080? of lifter preload. These is no sacrifice of low-end power, and the power holds on beyond the power peak much more noticeably. We have expressed this in previous newsletters, and several magazine editors and independent tuners have corroborated our findings. It is our opinion that improper (inadequate) lifter preload is one of the major causes of valve spring failure (regardless of manufacturer and spring design) on LS1 engines (especially because of the significant thermal expansion properties of the aluminum engine castings).


Jake

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