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. Sold in pairs
It is always a good idea to check BEFORE tech!
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I ordered these springs to have a baseline on my spring tester and they were a perfect 10.8lb @.850 and 18lb @ .650. I've tested these springs compared to multiple other springs and for a right out of the box, ready to go product these are what your looking for. Inexpensive and accurate. Run them a few races and grab another set.
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