WarWagon, thats my understanding as well. I've never shimmed a pedestal mount rocker. Torque 'em down to 24 ft. lbs. make sure you can still turn the push rod with your finger and thumb. Too much free spin then you needed a longer pushrod, couldn't spin it, shorter pushrod.

 

OK if the valve is set to factory height and the pedestal rocker is bolted down, you should have the proper geometry. Ford already figured that part out for you. If the valve is set to high (to many valve jobs etc.) then the geometry is off and you have a good chance of wearing out the guides.....

Now if you deck the block .030 and shave the head .030 the push rod will be tooooo long and put too much preload on the lifter. The geometry won’t change just the preload. But like I said if you float the valves you stand a good chance of bending valves with lots of preload.


So let’s say you build a motor and the machine shop did the heads to factory spec. But they took .010 off the heads and you’re using thinner head gaskets. You put the motor together and start to put the rockers on. In most cases you would just bolt down the rockers and run it but here we removed some material from the heads and we are using thinner gaskets. You go to tighten the rockers down and find you are getting 1 1/2 turn of preload before the rockers seat on the heads.

You could shim the rocker higher but that would change the geometry and we don't want that. To do it the right way you should get shorter push rods to fix it. I have never had to use shims but I always check the preload, like I said before if I get 1/4 to 3/4 turn of preload I’m good.

The only time you should use shims under the pedestal mount rocker is if the valves are installed higher for some reason…..


Hey I’m learning things too. I have never run pedestal rockers myself I always use adjustable setups. But have rebuilt a few with them, never had any problems with the rockers.

Bottom line is if the valves are installed properly and the heads and block are stock you should be ok…..
If you have to shim the rockers the valves are too high….or the wrong ones……..


So shimming the rockers does change the geometry but you don’t want to shim them because you have to much preload, you shim them only if the geometry is off

 

HemiEater.........I totally agree.

 

I'm so glad there's someone (HemiEater) that enjoys typing more than I do . Nice job, BTW.



Pete