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Discussion Starter · #1 ·
my friend has shown pics of his exhaust cam that has snapped. it seems to have snapped between at valves 2 and 3. the cam cap jas also snapped in half. has anyone experienced this or know what might have caused it. tomei 272 10.8. supertec springs and retainers. help shedding light into possible causes would be appreciated. std cam cap bolts. i am waiti.g for cylinder head to see more detail.
 

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Discussion Starter · #3 ·
he has a manual that he uses. he normally does things step by step. could be but i doubt it. will ask him in any case.
 

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Sounds like the caps were not tightened down properly and have worked loose over time causing the cam to snap. The only other time I see cams snap is when the a timing belt/pulley or chain fails.
 

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I would surmise that the cams were torqued down in too few steps, the bending overload on the cam initiated a crack. Then it fatigued under normal running and finally snapped once the crack had grown to a critical length taking out the cam cap on failure.

On higher lift cams with stronger springs you need to tighten and loosen slowly and in the right order to prevent the valve springs overloading the cam in bending.
 

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Discussion Starter · #10 ·
upon closer inspection , i think the torque on the cam cap was incorrect as one of the bolts did not snap leaving me to believe it turned itself out over time.
 
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