dieselace74

Hello everyone. I just received my cylinder head replacement from Autozone and i will be installing it this weekend. Fingers crossed it goes smoothly. Anyway, I opened the crate and there was a note in it that stated valves adjustment needed after installation. I did a quick search and I couldn't find any info on the matter. Does anyone have an idea whats up? thanks!

dans98xj

as far as I know there is no valve adjustment on the 4.0. I remember torquing the rocker bolts down to 26 of 27 foot pounds and that was it.

dieselace74

I kinda figured, I just wanted to check and see if anyone had anything different to say.

CCKen

The adjustment they refer to is the lifter preload check/adjustment (with shims if required).


The rocker arm cap screw torque is 21 ft/lbs. Each cylinder/piston should be at top dead center compression when torqueing the cap screws to prevent bridge twist. The preload is also checked at TDC compression.


There's an art to this preload checking business.


Crane cams has the procedures and I have some pics somewhere to help.

dieselace74

ok, so pretty much turn the engine manually to get each cylinder to TDC, torque down the rockers and check for preload per Crane cams procedures. I still hae to go search for those procedures but is thats about it, it shouldn't be too bad

CCKen

You will be checking preload as you torque down the cap screws.


Crane has two procedures. The one I prefer is the cap screw turn method (1/2 to 1 turn).


The desired preload is between .020" and .060"


See pic below.


You'll install the bridge, pivots, rockers, and cap screws over the push rods. Slowly turn each push rod while slowly turning down the cap screws until resistance is felt in the push rod turning.


Mark the cap screw with index marks as shown in the pic. Alternate tightening the cap screws until they bottom out, then torque them to 21 ft/lbs. Observe the index mark position. This will show you the preload on the lifters.

CCKen

Crane Cams lifter info:


http://www.cranecams.com/uploads/instructions/151g_.pdf

dieselace74

thats great info, thanks! but after pulling the head off the cylinder walls and pistons were in bad shape. I decided to just pull the engine and take it to get rebuilt tmw morning.