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I can’t imagine those little springs would have survived very long trying to maintain control of the now heavier valvetrain with repeated high rpm use.
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This was my first thought as well...the springs that come with the Eddy heads are made for flat tappet lifters. They are not made to handle a much heavier roller lifter. Even mild roller cams like what the OP described would need more spring. I would not go back to that builder again....