Im switching out the heads on my LS1 for some 317's and Im going to put some Yella Terra rockers and some hardened push rods in. My question is do I need to check the pushrod length if I use the adjustable rockers? The heads have not been milled.

OR

Can I just buy the non-adjustable ones and use stock length push rods?

I'll be using and LS6 cam also.

Thanks!

 

u should always check the length but if your going with adjustable rockers u really dont have to be so precise with the pushrod length. and the only thing that scares me is that u had the heads milled

 

You will need to measrue your psuhrods either way.

With the adjustables you need to determine the push rod length that puts the preload within the range of adjustment bulit into the rocker.

Wtih the non-adjustables, of course, the push rod length determines the pre-load and therefore, should be measured.

 

The heads have not been milled.

So if I get the non adjustable ones I will only have to screw with it once to determine the correct length and then any time after that I will be able to just remove the rockers and reinstall them with out setting the rockers up again?

 

Yes the pushrod process is generally a one time process. The exception being if you change something in that affects pushrod length significantly. (Insignificant changes get lost in the preload specification, which is a range as opposed to a single value.)

 

With adjustables, the pushrod length determines both the wipe pattern and the preload, i.e., you need a length that at the proper preload gives you a good wipe pattern. With non-adjustables, the wipe pattern is set with rocker height adjustment (shimming or reducing rocker stand height) and then the pushrod length determines preload only after the rocker height is correctly set.

 

Ok now I am really confused. So how do I determine what push rod length to use with adjustable rockers since they are adjustable? Should I just use stock length push rods with my LS1 block /317 head combo?

 

https://ls1tech.com/forums/7957678-post2.html

 

I read that but I still don't get where you start when you have adjustable rockers? Where does the rocker get positioned height wise?

 

See

http://www.kustombitz.com.au/UserFil...kers-page1.pdf

And Attached

Basically, you determine the pushrod length that gives the proper wipe pattern, and then use the adjustment feature to dial in the preload. There are many previous threads on the wipe pattern details.

 

Ok that still didn't really answer my question. I guess I just don't understand how to set up the adjustable rocker when you are trying to check push rod length.

Stock ratio is 1.7 correct? I will be using the 1.7 yella terra rockers. Should I check push rod length with a stock one to get the length and then use the adjustable part of the rocker to set preload?

Sorry if I'm missing the info I'm looking for in your posts, maybe Im just retarted...LOL

 

You can use your stock pushrod as a stating pooint but, you should check the pushrod length using a "pushrod length checking too"l, which is essentially an adjustable length pushrod. These are available from any supplier selling pushrods (Manton, Summit Racing, Jegs, etc,) It allows you to try different pushrods lengths to check the wipe pattern. The is a trial and error process that ends once you determine the correct length/wipe pattern.

 

If I am not mistaken, the YT adjustable rockers bolt down and the adjuster is on the pushrod cup, correct?

 

Correct. See illustration behind link in post#10.

 

Check the wipe first with check springs and a dial indicator. In a pinch you can use a metal rule like a 6" fine rule. Here is how to do it, once that is done you can measure for pushrods. Note that the link has the head off the car, to do it on the car just make sure the piston is down the cylinder a few inches so there is room for the valve to open and close. Link

 

Ok I finally got around to actually checking my pushrod length and heres what I've come up with....

*Set engine to #1 TDC
*Install adjustable pushrod on intake side
*tighten yella terra rockers down snug with shims(to get correct wipe pattern on valve stem)
*to get to zero lash I have 12 turns

So 6.8 + (12x.050) = 7.4 plus .075 preload on an LS1 lifter = 7.475" pushrod length


Did I do this correct?

 

Where is the adjustment screw when you take the measurement? Since these are adjustable, and the valve stem geometry is set by the rocker bolt, you now need to ensure your adjuster bolt is correctly set as well.

 

Mine are the none adjustable rockers. I used the .047" shims supplied to get the wipe pattern in the middle of the valve stem and then checked my pushrod length.

Did I do this correctly?