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dldavis_66

Just picked up my Web Cam

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Lift: 370/350; Duration: 280/280 degrees; Duration @ 0.050: 256/256 degrees.

Can someone clue me in as to the 2 different durations?? I got an idea, but I'm not sure.

:smirk:

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No. Both sets of Durations cover both intake and exhaust xx/xx= intake/exhaust.

What I don't seem to understand is why there are 2 different Duration specs: Duration and Duration @0.050.

Here's the link. The profile I got was the second from the top #450/451:

http://webcamshafts.com/pages/motorcycle/honda/honda_xr_650_l_rfvc_(93-07)_sohc_4v.html

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The 280° spec is the "advertised" duration while the 256° spec is the duration measured from .050" after the valve opens to .050" before it closes. They have both because the higher advertised duration sells more cams to the uninformed(and technically it's not lying), but no real appreciable airflow starts until the valve is .050" off the seat. That's why the duration @ .050" is the spec that matters most.

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The 280° spec is the "advertised" duration while the 256° spec is the duration measured from .050" after the valve opens to .050" before it closes. They have both because the higher advertised duration sells more cams to the uninformed(and technically it's not lying), but no real appreciable airflow starts until the valve is .050" off the seat. That's why the duration @ .050" is the spec that matters most.

Ah hah.

Pretty close to what I thought it was....I think. I remember something like that from my high school Auto shop.

Thanks HT:thumbsup:

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