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Kirkham Motorsports

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  #1 (permalink)  
Old 04-27-2007, 11:20 PM
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Default Rocker Stud Wear

Could someone tell me if the wear marks on this rocker arm stud are unusual? If so, what is the likely problem? Could it be a too narrow rocker slot width? Motor is a 351W stroked to 418, Comp Cams roller with .576 valve lift, Comp Pro-Magnum rockers. Thanks.
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Old 04-29-2007, 02:05 PM
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Well, I could be out to lunch on this, but it looks like you don't have enough clearance for the lift you are pushing with that cam.
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Old 04-29-2007, 03:06 PM
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Default

You have exceeded the allowed space between the fulcrum point and the push rod cup. Or the roller to the fulcrum point.

I used to see them after the fact. Broken, the pushrod sticking through the top of the valve cover. A connecting rod out the side of the block.

You are lucky you decided to pull them.

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Old 04-29-2007, 04:07 PM
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Thanks for the replies. Do I understand then, that longer rocker studs should fix this? If longer studs aren't available, is there another simple fix? Also, how can I determine what the allowed space between the fulcrum point and the push rod cup actually is, so that I know how tall the studs need to be? I'd prefer to avoid trial and error if possible.
Thanks again.
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Old 04-29-2007, 04:29 PM
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The wear marks are not unusual

Jerry
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Old 05-17-2007, 08:42 PM
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Default Problem Solved

Just to close this out, the wear marks were caused by excessive clearance between the rocker stud and the hole in the rocker arm trunnion. This, in turn, was caused by the trunnion holes being too large. The holes should have been .438" in diameter, but were .003-.006" larger than that. This has been confirmed by Comp Cams (rockers are their Pro-Magnums), and they are rebuilding the rockers with new trunnions under the warranty. Their warranty guy said he had never seen this problem before.
Although I didn't say this in the original post (because I hadn't at that time examined all the worn studs), some of the wear was severe enough that you could easily feel a ridge on the stud with your finger. The rockers were really digging into the studs.
Thanks for the responses above.
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