These Box Stock class valve springs have been specially treated to prolong pressure retention. The pressure loss from fatigue is about half of what is seen with untreated springs. This will allow the engine to run a higher RPM for a longer time before experiencing uncontrolled valve float, requiring spring replacement.
The springs are made in batches of thousands of springs at a time and are designed to pass both the 10.8lbs @ .850 and the 18lbs @ .650" check. We have not found any that failed after dyno time, however, we do not guarantee they will all pass tech out of the box. It is always a good idea to check BEFORE tech!
These springs have a green stripe and are sold in pairs.
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They are great springs replacing the stock predator springs. Both 1st and 3rd generations predator engines. Simple and adds better valve control intake set at .003 and exhaust at .002
Of all the box stock springs I have tested these springs seem to last a race or two longer. I have consistently gotten 4 to six races out of these with my limited mod motors before they get week. They perform well into the 7100-7300 rpm range if you are jetted right. I have yet to see one break get week right away or get a dq out here in CA