got this from lloyd on pr length checking and thought i should share, if there is a better place for it please move. keep in mind i got this for installing 1.6 roller rockers in a lt1 which has 1.5 non roller rockers stock. enjoy.

PR length is something that you need to check to get the EXACT length. Use an adjustable PR checker and start at 7.100" and adjust the length until you get the wear pattern most centered in the valve. Go .050" shorter and watch the wear pattern move. If it gets worse, go .050 longer. It could be anywhere from 7.00 to 7.250 depending on everything done but a 7.100" (Trik Flow 21407100) is what I suggest for people that do not know how (or do not wanna take the time) to do this.

The following is a method of verifying proper valve train geometry. After you have estimated the required pushrod length using a Pushrod Length Checker, use this method to verify that the valve train geometry is correct (using the rockers you are using in your engine):



1
The first step is to install a solid lifter and an adjustable pushrod. Mark the tip of the valve with a marker



2
Install your rocker arm and set it up with zero lash.



3
Rotate the crankshaft clockwise several times. Remove the rocker arm. The contact pattern of the rocker tip will be where the marker has been wiped away from the valve tip. The pattern should be centered on the valve tip, and as narrow as possible. If it is not, experiment with varying the pushrod length to yield the best pattern.



4
Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip.



5
Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.



6
Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.

 

good info craby

only one question, whats the deal with hydraulic lifter etc, and specially on LS1 you wont want to pull the head to put a solid lifter in??

 

yah u have to use a solid lifter to get the right movement so a intake gasket change would be in order if doing it on a installed operating motor. have never tore into a ls motor,do u have to pull the head to get to the lifters?

 

yeah, the lifters are in plastic holders under the heads, no way to get them out without pulling it all, maybe you just compress the lifter?? idk ???

I read up about it when wanting to do a cam change, but to do lifters too but its a full heads off job so might as well wait and do heads cam oil pump lifters rods etc all at once and drop the engine out too maybe??

 

Looks like it adds a bit more of "fun" to the job...http://www.chevyhiperformance.com/te.../photo_01.html

 

doesnt the ls already have 1.7 rockers?

 

yeah, 1.8 are our upgrades, but most of cam ramp rates are too steep and 1.8 would be pushrod benders for sure

 

Ready set sticky, thanks for the info Craby!

 

good info