I just installed my CC 1.85 stud mount rocker arms. I tightened the nut till I had zero preload then added 1/8 turn. I was fine with this then I read some instructions for a set on Crane rockers and they wanted 2 full turns!! Anybody here use those rockers? what's everybody's opinion about how much preload does the lifter need. I don't want them hanging open (why I only put 1/8th turn) but dont want the lifter bleeding down and losing lift either.

 

I installed the Cranes, but the installation is specific to Crane and results from several things including the thread pitch on the stud. Doesn't CC have instructions? If not, check their web site or do a search to see if there any magazine articles on them and how they were installed. Not sure I would follow Crane's procedure, only because I don't know enough about your particular setup.

 

CC has just the standard "zero lash then 1/2 turn" I know the factory rockers have a ton of preload and so does the crane it seems, I night run the car as is and also try 1 full turn.

 

Do a search, but I seem to remember the lifter pre-load should be in the 0.080 vicinity. The aluminum block grows with heat so from what I have read more is better than too little. Vinci has done a lot of research on this, you might want to visit their web site and read some of their tech tips.

 

Doesn't it depend on how much preload a "turn" makes? I know the Crane rockers stud threads produce .015" of preload with each 1/4 turn, therefore, 1 full turn is .060 of preload.

 

I am beginning to think I will need more preload. I did notice the lifters bleed down very fast.

 

some lifters do bleed away quite fast, if i were you i would start the engine and see how it sounds. if the engine starts and runs fine without any lifter noise its ok, if there are lifters making noise you have to figure which ones are too loose by bringing each cylinder to TDC one by one and checking by finger if they are too loose or not. if you overtighten them you might have a misfiring engine or even and engine that wont start.

 

Looking at the CC web site, the studs look like there are 3/8-24 thread where the adjuster nut is. 1/8 turn is about 0.005" on the stud, which in my opinion, is not enough preload.

 

the amount of turns to get to a given preload depends on thread pitch of the stud.