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Cam Failure

 

Cam Failure Details

Page 1: Drivetrain removal    Page 2: Engine Disassembly    Page 3: Engine Assembly    Page 4: Drivetrain installation

Cam Failure Detail

(click on thumbnails for larger image)

Root cause: chamfer at base of tappet?

Cam lobes

1 Exhaust - Opening side / Closing side

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1 Intake - Opening side / Closing side / tip of lobe / Closing side again - there's a little galling on the opening side that you can't feel but can see, there's more galling on the closing side.

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2 Intake - Opening side / Closing side - just a touch of galling on the closing side just past the lobe

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2 Exhaust - Opening side rotating through Closing side - closing side badly galled

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3 Exhaust - Opening side rotating through Closing side - closing side badly galled

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3 Intake - Opening side / Closing side - you can see the galling just starting

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4 Intake - Opening side / Closing side

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4 Exhaust - Opening side (x 2) / Closing side

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Tappet detail (2 Exhaust tappet) - tappet diameter: 0.937", base diameter inside the chamfer: 0.885", as nearly as I can measure it.  Also, the base is slightly curved - if I place the base of one tappet against another, I can rock them a bit.

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Here's what stock tappets look like - the base it totally flat (if I put two together, there's NO rocking), and there is no chamfer to speak of at the edge

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Side wear pattern of a couple of the lifters pulled from the race motor:

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