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Rockers coming loose

Old 07-25-2011, 08:49 PM
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Default Rockers coming loose

I had a set of 454 mags rebuilt this spring with comp cams marine extreme cam flat tapit hydrolic lifters and magnum roller tip rockers, rockers like to back nuts out as soon as you bring moters over 4,200 rpm, got new nuts and locktited them down still backed off nuts this weekend. What is going on, is cam to much for rockers, did my moter builder mess up or what.
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Old 07-25-2011, 10:08 PM
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Doug,
Are you sure that the nuts are backing off or is the cam wearing badly and making the rockers loosen up ?? I personally cannot believe they backed off after you locktited them. Exactly which cam are you running ? Part number ? The rocker arm nuts should be pretty hard to turn on the studs, if not something is wrong. Are the studs worn out ?

And last but not least, if you paid someone to build the engine, why are you not asking him instead of us ? I must not be doing something right, if one of my customers had this problem I would definitely be the first to hear about it and to be honest with you I would want it that way.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md
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Old 07-25-2011, 10:40 PM
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are ALL the rockers loose are some of them? I have never run across anything like that before. I have had one back off but it was a bad nut that had lost its interference fit. if it is only some of them I am with Bill on this one, the cam lobes are probably going away.
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Old 07-26-2011, 05:20 AM
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If the rockers you have look sorta like stock ones with a fulcrum ball and a locknut that is similar to stock just spend 60$ on a set of poly locks from arp, my comp magnum rockers had poly locks that kept breaking below the allen lock and I switched them to the arp's and never had another problem. I know I tightened them pretty tight but it was the way I had done my whole life, Smitty
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Old 07-26-2011, 08:33 AM
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ok, ran into the same thing last year working on a pair of small blocks that we put vortec heads on, same deal, new studs, new nuts, very little resisitance when tightning..would back right off..found that the "new" studs were made a few thousants to small..gotta love this chinese JUNK !! had to switch to poly locks to cure the problem..
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Old 07-26-2011, 12:37 PM
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Default rockers

Ok i have comp part # 11-240-4 cams with their hyrdrolic lifters, i told my engine builder about the problem after 1 came loose on the starb moter he said it was a bad nut, replaced all nuts both engines and 1 came loose on starb and 3 in a row on outside port. going to try polylocks mabey studs are crapy, if it does not work going to have a melt down. moters run good so don't think cam is falling apart.
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Old 07-29-2011, 09:14 AM
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Originally Posted by dougman
Ok i have comp part # 11-240-4 cams with their hyrdrolic lifters, i told my engine builder about the problem after 1 came loose on the starb moter he said it was a bad nut, replaced all nuts both engines and 1 came loose on starb and 3 in a row on outside port. going to try polylocks mabey studs are crapy, if it does not work going to have a melt down. moters run good so don't think cam is falling apart.
Im not sure about that cam, but I believe once you get to a certain lift number, you can no longer use the stock nuts and just torque them to spec. You need poly locks and adjust the valves individually and set lash.

I learned this the hard way on a old Pontiac 400 years ago after some bent pushrods.
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Old 07-29-2011, 04:04 PM
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Default Fixx

+1

i have used the same set up in the past,,those rockers should have came with poly locs or at leaste mine did,,no troubles..
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