Yella Terra failure
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? I’m running a vrx5 cam with tfs215 heads.
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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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Joined: Jun 2016
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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.
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.
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.
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.
TECH Senior Member
Joined: Jun 2016
Posts: 22,308
Likes: 3,625
From: Central Cal.
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.
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.
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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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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