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Old 24-07-2008, 05:53 AM   #14
sandy309
106 RALLYE REGISTER ENGINE TECHNICAL ADVISOR

 
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I'm not sure about the legal implications, but there's no apparently accepted standard for measuring cam profiles. It's been common practice for years for profiles to be described according to where they fit in the range, rather than the actual duration etc.
I measure the lift curve at the valve, with the advised clearance (0.2mm for these), which is as close as possible to what actually occurs in use. With rockers, the exact lift profile at the valve isn't as consistent as with bucket followers and at speed, the valve movement will vary according to the flex and rebound of the valvetrain too.

I'm not sure about the legal implications, but there's no apparently accepted standard for measuring cam profiles. It's been common practice for years for profiles to be described according to where they fit in the range, rather than the actual duration etc, much like recent BMW 316s having 1.9 litre engines I guess!
I measure the lift curve at the valve, with the advised clearance (0.2mm for these), which is as close as possible to what actually occurs in use. With rockers, the exact lift profile at the valve isn't as consistent as with bucket followers and at speed, the valve movement will vary according to the flex and rebound of the valvetrain too.
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Last edited by sandy309; 24-07-2008 at 05:53 AM. Reason: Automerged Doublepost
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