Would adding yella terra rocker arms be worth it on my engine. I saw an add for them that said you pick up 10 to 20 rwhp depending on the setup.
Thanks for any info from anyone that has installed them.

 

I doubt you'll gain that much from the rockers, although they may help extend the life of your valvetrain.

Btw, it's "Yella Terra"...

 

Thanks for the info and the spelling lesson . I have to type fast at work .

 

Peace of mind. . . IF you set them up correctly and don't just bolt them on!

Mike V

 

i buddy has them on his car and said they where a good investment. . . i think i m going to pick up a set...

 

I have the ultra lites they are a nice!

 

As stated, don't buy them for hp, but them for valve train geometry. Take the time to set them up correctly noting you may need pushrods in the end. The YT instructions are very hard to follow and ls1howto is not correct for installation.

 

I have the ultralites and about ready to set them up. How do you recommend going about setting them up properly, vette? I've got a pushrod checker as well. I'm all ears...

 

Im considering buying a set as well, maybe pik up 5hp but they are quiet and dont hae any bearing to fall into the motor if they go out like stockers

Does the pushrod length really change?

 

The hard part is getting the push rod length correct. Have the rocker installed but not tight. Start thighing the bolt. Find the point that the push rod will not turn any more. The bolt should turn 1 1/2 to 2 tunrs after this point. You may have to do this a few times. Move the checker in or out. try again Once the checker is the right lenght measure it. Most people use the washer. If you do most people use 7.5. That is what is in mine. It was 2 turns with the heads milled .024

 

First is set the wipe pattern up correctly, then measure for pushrod length. If shims are required to get the correct wipe, then the pushrod length may change and should be measured. Here is how I did mine (copied from my post on Corvetteforum).

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I just finished setting up the wipe pattern of my Yella Terra roller rockers on my new AFR heads. The Yella Terra rockers are fixed fulcrum rockers (as opposed to a fully adjustable rocker like the Crane I set up on my current configuration) and are furnished with a rocker pedestal and a single shim that is 0.048” thick, which when placed under the pedestal, will raise the fulcrum of the rocker and move the roller location towards the exhaust side of the valve stem. The goal is to center the wipe pattern on the valve stem and minimize the width of the pattern. When the width is reduced over the course of rocker motion, then the side loading into the valve guides is also reduced. This not only provides faster valve motions but also minimizes valve guide wear. Below is a photo of how the Yella Terra setup is installed with the pedestal and shim (if used) under the rocker shaft and the bolt passing through the assembly and into the threaded hole in the head.







I am doing this on the workbench but this can also be done on the car. The workbench has the advantage that there is more time to set things up and if parts are needed the car won’t be down as it would if you were in the middle of the head installation. Plus, it’s easier on the back.

The first step is to remove two valve springs and replace them with checking springs. I have two sets of checking springs and I used the stiffer set since they provide more force against the rocker to help in wiping off the ink that is applied to obtain the final wipe pattern.






Once the check springs are installed, set the cylinder head in the air such that the valves can be manually operated without contacting the workbench surface. Using a dial indicator allows you to manually operate the rocker arm to the required valve lift. Since the final wipe pattern is lift sensitive, you have to ensure that the motion you are moving the rocker through imitates that which will be driven by the cam.

The next step in the operation is to setup your rockers and snug the bolts. There is no need to fully torque the bolts and load the threads in the aluminum head. Hand snug is fine and will eliminate thread wear as the bolts are taken in and out several times during the process. Once the rockers are in place with the shims that are being checked, and your measurement method is setup to determine how much the valve is being moved, use a Sharpie to spread black ink on the upper surface of the valve stem. I have found it best to not allow the ink to dry too long as with checking springs it doesn’t wipe off as well. Instead, I use a cotton swap and pull off most of the cotton then soak it with ink from the Sharpie. Then I simply rotate the rocker back off of the valve stem and apply the ink. After it is just dry, then the wipe test is conducted by rotating the rocker arm by hand in the same manner as the pushrod and cam would if the head were on the motor. This process is repeated until a satisfactory wipe pattern is found by adjusting the height of the shim. A thicker shim should push the wipe pattern towards the exhaust side of the valve stem. This will be critical later as the pushrod length changes approximately 0.016” in length for every 0.010” of shim you add to the rocker pedestal so that the wipe pattern needs to be established first followed by the pushrod length.






I started the process with no shim in place under the pedestal and then added shims until I got the desired wipe pattern. Washers can be used and stacked for this process but once a thickness is found you need to find a single piece shim of the correct thickness. In the photo below (sorry for the crappy photography), three of the patterns are shown. On the left is the wipe pattern without a shim. Notice that the wipe pattern is towards the intake side of the valve stem and barely gets to the valve stem center over the course of travel of the roller on the rocker. In the middle photo, shimming has now moved the wipe pattern towards the center of the valve stem. It is still biased to the intake side and a little wide. The final wipe pattern on the right is the shim setup I will use for final installation, as I am very pleased with the final wipe pattern obtained. Note that the shim value can be different for any given setup, the point being that simply bolting on the rockers from the box would have yielded the pattern on the left and likely resulted in not only disappointing results but higher than necessary valve guide wear for my installation. I bought my final shims (11/32" ID, 13/16" OD from McMaster-Carr, which are available in a lot of thicknesses. These were pretty much a perfect fit under the pedestal if you need a thickness that differs than the one provided by Yella Terra for any reason.

 

I used your write up to set up my Yella Terra's. Worked great! One of the reasons I got the YT was to quite down the valve train. In my case it didn't do that, otherwise I'm satisfied.

 

Thanks Vette! That is very good and easy to understand. Thanks for passing that on.

 

Any chance of making that a Sticky?

 

This is good for valve wipe how about push rod length?

 

Ok so dont' the shims affect the pushrod length? I put some shims in my yella terras and some don't have any shims and think am getting some extra noise from some of them now. I did get a pushrod checker and going to try to see what it says.
So the shims don't affect possibly noise just wipe?? I thought shims are also playing with the preload as it seems if you set them so you are under a full turn your preload might be a low .40 or something and think my ls7 need much higher so would think you should be getting 1/5 to 2 turns which should be more like .80 preload or am I wrong there.

I am wondering why I would need longer pushrods. Have stock afr heads and they said not change in pushrod lenght as their rocker pedestals are same as stock height even though thicker deck. And my cam according to lingenfelter is same as stock no change there. Do 1.8 make you need longer or shorter pushrods over 1.7s??

I just want a quiet valvetrain thinking of going to 1.7 yella terras if they will be quieter than my 1.8s.

 

I always use that guide when telling people how to do it. I have it saved on my computer.

 

Shims set geometry (wipe). But once the geometry is set, shims will also alter the pushrod required. Best to think of shims for setting geometry and then always measure for pushrod length.

 

I put my yt in with no shims today and its quieter it was noisy with the shims.
I used pushrod checker and pretty sure have around .060 ish for prelaod ,7.45 would put me think over .100 and 7.425 would put me at think around .080ish. It is worth going up to the 7.425 .I don't find it too loud. I thought if you go too high you lose compression or is that way over .100. Seen some post where guy was running like .160 and said he gained power?

Car is running pretty good now not sure if should touch anything .Am I just wasting time getting 7.425 or 7.45 then? Will it really get much more quiet from 060 ish to .080 or 0100? It was noisy with the preload figure around .010 ish with those shims in there. they in effect really shorten the pushrods..

 

This thread should be made into a sticky.

Very comprehensive and easy to understand.





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