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Yella Terra failure

 
Old 05-18-2019, 03:28 PM
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Default Yella Terra failure


You guys think I should just try to replace this one and hope it was a defect or get a better set of rockers? Iím running a vrx5 cam with tfs215 heads.
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Old 05-18-2019, 03:32 PM
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how long ago did you get these
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Old 05-18-2019, 03:36 PM
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I bought them used with the heads a little over a year ago. I would guess theyíre about three years old.
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Old 05-18-2019, 04:16 PM
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Pay a visit to Harland Sharp or upgrade the stock rocker arms to bronze bushings.
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Old 05-18-2019, 04:29 PM
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stockers with Straub bushings... at least thats my answer
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Old 05-18-2019, 04:40 PM
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I wanna run stockers with trunnion upgrade but trick flow said roller rockers are required with their heads with bronze guides.
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Old 05-18-2019, 04:58 PM
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the geometry should be much better with aftermarket rockers
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Old 05-18-2019, 05:06 PM
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Those are an earlier design of the Yella Terra rocker. Look for photos of the earlier design and the Gen III design, which has been beefed up. I would re-install Gen III Yella Terra's myself.
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Old 05-18-2019, 05:13 PM
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Originally Posted by td1168 View Post
I wanna run stockers with trunnion upgrade but trick flow said roller rockers are required with their heads with bronze guides.
Did they give a recommendation as to what you should be running on their heads?
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Old 05-18-2019, 05:27 PM
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ahh gotcha... then I would just get the new style Yella's
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Old 05-18-2019, 06:09 PM
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Originally Posted by vettenuts View Post
Those are an earlier design of the Yella Terra rocker. Look for photos of the earlier design and the Gen III design, which has been beefed up. I would re-install Gen III Yella Terra's myself.
this is why i wanted to know how old they were
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Old 05-18-2019, 06:25 PM
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Stockers - CHE Bushed gets my vote. After much discussion with Darin Morgan, he concluded same.
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Old 05-18-2019, 07:00 PM
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Originally Posted by dr_whigham View Post
Stockers - CHE Bushed gets my vote. After much discussion with Darin Morgan, he concluded same.
Even with bronze guides? I've always heard they don't like the side loads non-roller tip rockers impose on them
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Old 05-18-2019, 07:12 PM
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Bronze wears slowly. Powdered metal... Once it starts to wear, it's very quick. AFR says stock (bushing upgraded) rockers are fine. I ran them on my AFR 205's @ .631 lift.
I'll run them on AFR 260's @ .632 lift if I wind up getting them.

That's just the conversation we had. When I was thinking about having Darin do my LSA's (and I still might) he wanted me to go with CHE guides and stock rockers.
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Old 05-18-2019, 07:20 PM
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I never cared for those rockers. You can see from the pics that the metal crystalized. Metals will crystalize under wear and stress and fracture along the crytalization line. In otherwords, the metal or heat treating process was below the grade for the anticipated stress.

Since this did not happen to all of the rockers, it tells me Yella Terra has either quality control problems or engineered the product too close to the safety line to save money. Well engineered products engineer in a safety factor of 20% greater than the anticipated loading.

Look at Cranes, Howards, or Crower if you think you should stick with a roller tip.
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Old 05-18-2019, 07:27 PM
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Originally Posted by dr_whigham View Post
Bronze wears slowly. Powdered metal... Once it starts to wear, it's very quick. AFR says stock (bushing upgraded) rockers are fine. I ran them on my AFR 205's @ .631 lift.
I'll run them on AFR 260's @ .632 lift if I wind up getting them.

That's just the conversation we had. When I was thinking about having Darin do my LSA's (and I still might) he wanted me to go with CHE guides and stock rockers.
Interesting! I've always thought the CHE/stock rocker combo would be a winner. Wasn't sure about that with bronze guides. Thanks!
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Old 05-18-2019, 07:45 PM
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The new Texas Speed rockers intrigue me to be honest. I think they said an additional 8 grams over the nose? Since I limit my LSA to 6800rpm MAX, that might be an option for those of us not revving to the moon
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Old 05-18-2019, 09:20 PM
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This used to be a really common problem with aluminum rocker arms in general, in race motors they used to toss them out after a season or less of use.. Way back ,, engine builders really avoided the AL rockers because street drivers would run them too long.
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Old 05-18-2019, 10:39 PM
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I don't think many guys realize how limited a lifespan aluminum rockers have compared to steel ones. They fatigue out. Same as with aluminum connecting rods.
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Old 05-19-2019, 03:05 AM
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