C6 - Yella Terra Ultra Lite installation
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Safety Car
Joined: Jun 1999
Posts: 3,570
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From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
C6 - Yella Terra Ultra Lite installation
Because I have a relatively high lift Lingenfelter GT-11 cam, I decided to upgrade the rocker arms to the Yella Terra Ultra Lite. The cam specs are 215/231 degree duration @ .050" with and .631"/644" lift and118* LSA. I noticed a random "tick-tick", so I felt it was time to check out the rocker arms and make a change if necessary after 10,000 miles.
Here are some of the photos.
1) Yella Terra Ultra Lite roller rockers unpacked, cleaned and ready to install. I first soaked and shook the new Yella Terra's in a plastic bucket filled half way up with mineral spirits. I did this to clean out any left over machine oil and small metal shavings left over from the machining process. I found small aluminum chips in the bucket and the roller tips seemed to move much more smoothly so it was worth doing. Two rocker arms were rubbing slightly on the shaft "C" clips so I pressed in the fulcrum roller bearings a few thousands to get them to provide clearance. Before installation, I soaked them overnight in engine oil to lubricate the roller bearings.
2) Comparison of the new rockers on the left and the OEM rockers on the right. Although the Yella Terras look huge, they are light weight aluminum. The center fulcrum bearing is a lot bigger in diameter but since the center shaft does not move, it does not add significant reciprocating mass. Pairs of rockers are on a common shaft which keeps them aligned and reduces deflection due to the increased stress from the more aggressive GT-11 cam.
3) Here is a shot of the OEM rocker that was twisted. Each individual OEM rockers pivot on its own bearing and bolts into a semi-circle saddle on a stand-off strip running the length of the head. Apparently, the OEM saddle got twisted some how causing the rocker to be mis-aligned with the valve. Left alone, I think it may cause more valve guide wear than normal.
4) Here is a picture of the normal wear pattern on an OEM rocker. Notice it is evenly worn although the wear pattern at maximum lift is close to the nose.
5) Here is a picture of abnormal wear which appeared on 4 OEM rockers. Notice the half-moon shaped groove starting to develop near the nose of the rocker. The wear on the rocker was significant and don't think this is good. Perhaps this was the source of occasion louder tick-tick than normal.
[IMG]
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Before I started the installation, I made sure I understood how to properly set them up. There is a lot of bad information out there so I be careful.
When buying new rockers, make sure to also get an adjustable push rod length checker. Comp Cam sells them for $20. You need this to figure out the both the rocker arm shims and push rod length.
The Yella Terra comes with 16 .040" shim washers but you may need difference thickness shims from McMaster-Carr.
If the new rocker arm is set up too low, the tip pushes contacts the intake side of the valve first and sweeps too far over the valve stem. If the rocker arm is too high, it will contact the valve stem on the exhaust side first and sweep toward the intake side and will also be wide. The impact can be excessive valve guide wear. The rocker arm sweep pattern should be over the center of the valve stem and as narrow a sweep as possible to keep the side thrust on the valve guides to the minimum. See the photo below.
A lot of folks don't understand the importance of getting the rocker arm geometry correct first. At the bottom of this thread are links to the Comp Cam website that will help explain it.
The push rod length is only to get the correct lifter pre-load. Each rocker arm manufacturer has their own procedure but Yella Terra's say it should be between 1/4 to 1 full turn after zero lash.
Do not even think about the determining the final push rod length until the rocker arm height is right or it will be wrong. Don't listen to those that say always use 7.xxx inch push rods. The only way to do it right is to follow the manufacturer's set up procedure.
COMP CAM PUSH ROD INFO
COMP CAM VALVE TRAIN GEOMETRY
Here are some of the photos.
1) Yella Terra Ultra Lite roller rockers unpacked, cleaned and ready to install. I first soaked and shook the new Yella Terra's in a plastic bucket filled half way up with mineral spirits. I did this to clean out any left over machine oil and small metal shavings left over from the machining process. I found small aluminum chips in the bucket and the roller tips seemed to move much more smoothly so it was worth doing. Two rocker arms were rubbing slightly on the shaft "C" clips so I pressed in the fulcrum roller bearings a few thousands to get them to provide clearance. Before installation, I soaked them overnight in engine oil to lubricate the roller bearings.
2) Comparison of the new rockers on the left and the OEM rockers on the right. Although the Yella Terras look huge, they are light weight aluminum. The center fulcrum bearing is a lot bigger in diameter but since the center shaft does not move, it does not add significant reciprocating mass. Pairs of rockers are on a common shaft which keeps them aligned and reduces deflection due to the increased stress from the more aggressive GT-11 cam.
3) Here is a shot of the OEM rocker that was twisted. Each individual OEM rockers pivot on its own bearing and bolts into a semi-circle saddle on a stand-off strip running the length of the head. Apparently, the OEM saddle got twisted some how causing the rocker to be mis-aligned with the valve. Left alone, I think it may cause more valve guide wear than normal.
4) Here is a picture of the normal wear pattern on an OEM rocker. Notice it is evenly worn although the wear pattern at maximum lift is close to the nose.
5) Here is a picture of abnormal wear which appeared on 4 OEM rockers. Notice the half-moon shaped groove starting to develop near the nose of the rocker. The wear on the rocker was significant and don't think this is good. Perhaps this was the source of occasion louder tick-tick than normal.
[IMG]
Before I started the installation, I made sure I understood how to properly set them up. There is a lot of bad information out there so I be careful.
When buying new rockers, make sure to also get an adjustable push rod length checker. Comp Cam sells them for $20. You need this to figure out the both the rocker arm shims and push rod length.
The Yella Terra comes with 16 .040" shim washers but you may need difference thickness shims from McMaster-Carr.
If the new rocker arm is set up too low, the tip pushes contacts the intake side of the valve first and sweeps too far over the valve stem. If the rocker arm is too high, it will contact the valve stem on the exhaust side first and sweep toward the intake side and will also be wide. The impact can be excessive valve guide wear. The rocker arm sweep pattern should be over the center of the valve stem and as narrow a sweep as possible to keep the side thrust on the valve guides to the minimum. See the photo below.
A lot of folks don't understand the importance of getting the rocker arm geometry correct first. At the bottom of this thread are links to the Comp Cam website that will help explain it.
The push rod length is only to get the correct lifter pre-load. Each rocker arm manufacturer has their own procedure but Yella Terra's say it should be between 1/4 to 1 full turn after zero lash.
Do not even think about the determining the final push rod length until the rocker arm height is right or it will be wrong. Don't listen to those that say always use 7.xxx inch push rods. The only way to do it right is to follow the manufacturer's set up procedure.
COMP CAM PUSH ROD INFO
COMP CAM VALVE TRAIN GEOMETRY
Intermediate
Joined: Sep 2010
Posts: 30
Likes: 1
Hi. I currently have the lingenfelter gt11 cam in my ls2 also and it also makes the tick tick noise but thats because of the very high lift of the valves. The stock rocker arms are fine as long as the geometry is set correctly.
Im changing my cam to the lingenfelter gt1-1 next month
229/242 631 .631 114.LSA
THe GT11 cam is ok but I find the torque curve is not peaky enough. Its too linear in its delivery.
To be honest I prefer the stock cam power delivery as it was a 116LSA and it was a bit more hardcore but produced less power and torque through the rev range.
Also doing a head conversion using the l92 heads with head work and compression ratio bumped up to 11:5.1, FAST 102mm inlet manifold,
Im port matching the throttle body and the manifold too.
Will be interesting to see how the lingenfelter gt1-1 cam performs. Should have a much peakier torque curve.....
Im changing my cam to the lingenfelter gt1-1 next month
229/242 631 .631 114.LSA
THe GT11 cam is ok but I find the torque curve is not peaky enough. Its too linear in its delivery.
To be honest I prefer the stock cam power delivery as it was a 116LSA and it was a bit more hardcore but produced less power and torque through the rev range.
Also doing a head conversion using the l92 heads with head work and compression ratio bumped up to 11:5.1, FAST 102mm inlet manifold,
Im port matching the throttle body and the manifold too.
Will be interesting to see how the lingenfelter gt1-1 cam performs. Should have a much peakier torque curve.....
Burning Brakes
Joined: Jul 2009
Posts: 785
Likes: 10
From: Sarasota,FL & NW Indiana
LS7 Rockers
I found the instructions from YT to be confusing. Here is a post on my installation where the YT supplied shims were not thick enough. Link
Running into same problem on a LS7. Any shims available for the half moon shaped pad.
Thanks in advance
Jim
