What could cause this?

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yedister
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Got a call from the guy working on the Vette. He has it on the dyno, he said that after a few pulls on the dyno that the valves are getting noisy. Sounds like that they loosen up. Is that normal? I have a Jesel Shaft Rocker setup. The shaft assembly was removed back in January to change to the bushed lifters, new length pushrods were needed, went from a 6.8 to 8.6 inch. The changed was performed by a mechanic that is a serious racer. It has no run time on the motor after he adjusted the lash and drove out of the shop.

Thanks for your assistance

Poncherello
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Have you checked for misaligned rods? Valves may be loose in their bores and/or weak springs.

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yedister
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That was all checked after the lifter changed

yedister
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# 7 intake and # 8 Exhaust needed adjustment. No other problems found.

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ArKay99
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I had Jesel's on my vette some time ago. I don't know if the ones you have were the same model as the ones I had. The ones I had were only designed to be used with stock diameter springs and cups. The problem was in the geometry. Since they were aluminum they had a much fatter cross section and had just enough clearance for the stock spring setup. I was using AFR heads with heavy tension dual springs and the top cup was interfering with the arm's movement when it came to rest. I was getting valves not closing all the way or getting hung open and getting backfires and the piston bumping the valve. I had to have them undercut for clearance and everything was fine after that, although I eventually took them off and put Yella Terras on as I was always a little leary of an arm cracking at the stress point. The Jesel's were a great shaft rocker otherwise. The reason I mentioned all the above was because what happened to you happened at first to me.

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yedister
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Interesting and good info. Thanks


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