Yella Terra install
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
Yella Terra install
How many of you had to use the shims in the kit. I have stock height Darts and a comp cam and IF I did it correctly, I'm not having to use the shims.
There are SOO MANY variations of the install that I'm not exactly sure. I put the cylinder I was going to "test" on off lobe, then installed the rocker pair. I turned the bolts by hand until I couldn't turn them anymore (0 lash) then counted the turns until it "bottomed out" (not torqued down) It took 1 3/4 turns. That just happened to be the exact amount it took when I "tested" the stock rocker (loosened it then counted the turns to bottom out)
Am I there are do I need to skim???
There are SOO MANY variations of the install that I'm not exactly sure. I put the cylinder I was going to "test" on off lobe, then installed the rocker pair. I turned the bolts by hand until I couldn't turn them anymore (0 lash) then counted the turns until it "bottomed out" (not torqued down) It took 1 3/4 turns. That just happened to be the exact amount it took when I "tested" the stock rocker (loosened it then counted the turns to bottom out)
Am I there are do I need to skim???
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Use the shim to set wipe, not preload. The Yella Terra instructions are confusing at best. If you don't have the ability to install a checking spring, another way to get a feel for the wipe is to leave the pushrod out and put a wipe of grease on the roller of the rocker. Install the rocker and then tap the roller against the valve stem. It will leave a line. The line should be approximately 0.025 from the center of the valve stem. Even though you have hydraulic lifters, I would also put some sharpie on the valve stem, install the rockers to about 5 ln-ft and then roll the motor over by hand a couple of times to check wipe. As the lifters bleed this method will provide less accurate results.
On stock heads, the only way i found to obtain a correct wipe was to use the provided 0.048" shim. When I recently set up my AFR's, I needed more shim to get the wipe correct. Note that use of the shim will alter the lifter preload.
On stock heads, the only way i found to obtain a correct wipe was to use the provided 0.048" shim. When I recently set up my AFR's, I needed more shim to get the wipe correct. Note that use of the shim will alter the lifter preload.
Last edited by vettenuts; Mar 1, 2008 at 04:24 PM.
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
Yes; this is definitly harder than it should be.
1.The Yella Terrra instructions say to use push rod length to adjust wipe, and to use the shims to adjust preload. They say that you should only have 1/2 to 3/4 turn from 0 lash to 25ftlbs.
2.Ls1howto also says to use the shims for preload, but says from 0 lash till the bolt "gets tight". If more than 360 degrees, add shims, less,you're OK.
3.A well known tuner on the forum PM'd me and told me that you must have AT LEAST one full turn, but less than two. 1 1/4 - 1 1/2 was about right. (remember that was where the stock ones were)
So you see where I'm getting a little confuesd
I certainly don't want to have too much pre-load and take a chance of bottoming out in the lifter
1.The Yella Terrra instructions say to use push rod length to adjust wipe, and to use the shims to adjust preload. They say that you should only have 1/2 to 3/4 turn from 0 lash to 25ftlbs.
2.Ls1howto also says to use the shims for preload, but says from 0 lash till the bolt "gets tight". If more than 360 degrees, add shims, less,you're OK.
3.A well known tuner on the forum PM'd me and told me that you must have AT LEAST one full turn, but less than two. 1 1/4 - 1 1/2 was about right. (remember that was where the stock ones were)
So you see where I'm getting a little confuesd
I certainly don't want to have too much pre-load and take a chance of bottoming out in the lifter
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
These are fixed fulcrum rockers, pushrod length will not affect the wipe pattern at all (unless they are so long they hold the valve open). Unfortunately, the instructions cover all of their products only in a general sense and they are very misleading (I am being polite). You need to set wipe first, then figure out the pushrod second.
PS: LS1howto is wrong too.
PS: LS1howto is wrong too.
Safety Car
Joined: Jul 2004
Posts: 3,904
Likes: 29
From: Vancouver Washington
I installed 1.8 YTs on my 01 LS6 without shims. The wipe came out perfect and I ended up with about 1 1/4 turn to 25 lbs. I used Comp 7.4 pushrods, PAC 1518 springs, and titanium retainers.
