I've always heard that LS1 rockers dont require any lash adjustments or any valves to be TDC. I just recently replaced a stock rocker and it was easy, just unbolt the old one and torque the new one down to 22ft/lbs. Its the same with aftermarket rockers right? I found one install guide that confused me. Do I have to do this?

http://www.ls1howto.com/index.php?article=21

Another guide for installing SLP 1.85 rockers doesnt mention anything like this

 

Stock rocker geometry is set by the rocker pad and support from the factory by design, as soon as you go aftermarket all bets are off. I think that is why the LS1howto web site is stating to verify the wipe pattern to ensure that it is correct. In the end, don't assume anything, that's how you end up with problems.

 

Okay...but I'm trying to figure out how to install aftermarket non-adjustable roller rockers. Do I adjust the lash, or simply bolt them down like any other bolt.

SLP 1.85 install guide doesnt mention anything about spring height, TDC, or adjusting.
http://www.fbody.com/tech/details.cgi?id=51

 

Two things need to be verified. One is the valve train geometry or the rocker wipe across the valve stem, the other is the lifter preload. With a non-adjustable rocker, the pushrod length will determine the lifter preload, the height of the rocker base sets the geometry. I am not familiar with the SLP rockers, which are supposed to be similar to the stock design. I guess what I am trying to convey is don't take what SLP tells you or doesn't tell you for granted, ensure for yourself the setup is going to be correct. The other thing to keep in mind is that the stock bolt down setup works within tolerance limits of the head/rocker/valve stem but is not necessarily optimum. You may find it can be improved upon the result of which can be better valve guide wear and maybe a few extra ponies up top.

 

I have those Terra Yella rockers. Like "vettenuts" said the "the height of the rocker base sets the geometry" if you use the stock lifter base you don't have to worry about preload however with the yella's you have to replace the rocker base with pedestal style base. The Rockers come with a shim that you can use under the base to ensure you have the proper preload. When I installed mine I did not check the preload, however I did the wipe test, the rocker seem to be pretty centered so I left the shims off. Since I have an upgraded valvetrain I set my rev limiter at 7K. A couple of days later I went to the track. On my second pass I decided to rev it higher from second to third, When the car reached 6,200 rpms or so it fell on it's face and the motor stumbled bad, then as the rpms drop it recovered, it even threw a code for a few seconds. After nursing the car to the pits I checked around to see if I was any apparent problem. I did 2 more passes after that without revving as high without any problem. I even got a new best time and mph. It appeared I was having some valve float so I took the covers off and decided to recheck my rockers. I have a big cam coming and I wanted to get this fix before putting it in (I really do not want to have any valve float with a high lift cam and run the risk of tagging a piston with a valve). After checking it I realize that I had too much preload so I put the shims (my preload was around 1/4 turn with the shims), did the wipe test again (it was perfect this time) and went out on the street to test with HP Tuners. I revved the engine to the limiter @ 7K rpms in first and no problems shift to second and do the same and no problem at all. No sign of valve float or any problems I did find out that my tach is lazy, compared to what HP tuners was telling me it was reading from the PCM, so I need to reset my shift light, use that and ignore my tach.

In short if the aftermarket rockers you choose use a different base than stock check your preload!

 

Thanks for the info guys. What did you do before you started the install to get one piston with 2 valves completely close??

 

yes, I turned the engine until the first 2 valves where completely closed in the drivers side.

 

What exactly is the point of this? If you didnt do it would it f up the install?

 

The idea is to determine the amount of shimming needed for proper valvetrain geometry. From what I gathered above, the lifter preload is determined by pushrod length. Rocker alignment on the spring (wipe pattern) is determined by the rocker installed height (adjustable by shims or machining the head). The reason they do this on the first two springs is to determine whether or not shims are required. Once you figure out the first two springs, it should be the same for everything else. Therefore, you don't have to do it on all 16 - just the first 2. If you can't get the right wipe pattern on the spring with the right preload (regardless of what shims you do or don't use), you may need different length pushrods. Hopefully, I've understood everything and speak the truth....

 

Reviving this from the dead JUST to say THIS IS WHY FORUMS ARE INVALUABLE ARCHIVES!!!

Thank you from the distant future, this helped me understand it all easily!