question about 1:6 rollers

[carbed87]

im putting crane 1:6 roller rockers on my cast iron gt-40 heads, just wondering if i needed a different pushrod legnth...if so, what legnth?

as you know the gt-40's are ped mount, so is there any special way to adjust them? i've tried just tourqing them down, and they ticked like a mofo, i also had no power. so how should i install them

 

[Foxfan88]

hmmm i am pretty sure the pedestal mount Rockers are not adjustable at all.... at least i am have always read and heard.

not sure on pushrod length, that starts to change when you mess with springs and the like

 

[carbed87]

thats not what i heard, this mechanic at my local ford dealer said i had to pull the lower plenum off and wach the lifter depress 20 thousands of an inch. thats while the its on the heel of the cam

 

[Dbeck002]

You should get a pushrod length checker to know for sure.


Do you know how to do the zero lash adjustment with the adjustable pushrod?

 

[carbed87]

yeah i know, people have told me that, but its a ford production head, i shouldn't have to right? i don't know, mabye someone who knows for sure can chime in on this

 

[8950HO]

You won`t know if you need different length pushrods until you go to install the rockers.(when I installed Crane Cobra 1.7 rockers on my E7 heads,I needed longer pushrods because I couldn`t get enough preload on the lifters).

Pedestal mount rockers are "adjustable" by using shims or different length pushrods.

With the lifter on the heel of the cam,tighten the rocker arm bolt by hand easy until theres no play,(zero lash),then tighten the bolt down with a ratchet counting the number of turns after zero lash that it takes to tighten the bolt to the head.
For the street you want ideally 1/2-3/4 of a turn past zero lash for the correct lifter preload.

If you get a quarter turn or less after zero lash you need longer pushrods.(.050" longer than stock should do it).Stock length is 6.250".
If you get more than 3/4 of a turn after zero lash you can use shims under the pedestal.

Don`t listen to anybody who says just bolt them down blindly without checking for the correct lifter preload.This is not the proper way to do it.

 

[carbed87]

yeah i found that out cause i did it, and obviously it didn't work too well, say, do i have to physically chect the lifter preload, or can i judge it by how much of a turn it takes to bring me itno tourque?

 

[8950HO]

yeah i found that out cause i did it, and obviously it didn't work too well, say, do i have to physically chect the lifter preload, or can i judge it by how much of a turn it takes to bring me itno tourque?

You have to get the right preload.
Get the zero lash point,(this is when you tighten the bolt down easily by hand until you can`t move the rocker arm up and down by hand).

From this point you count the number of turns it takes until you feel the bolt snug down to the head,(this is your preload on the lifter).

After you establish the snug down point of the bolt and finally get the right preload,then you torque the bolt to the final spec.
(it`s a little hard to understand if you`ve never done it but once you feel the bolt snug down with a ratchet after zero lash you`re preload figure is reached but the rocker bolt is not at the final torque spec).