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valve travel

1345 Views 5 Replies 5 Participants Last post by  Don Dorfman, 
mcoolidge56
My question is about a 2008 twin cam 96. Can anyone tell me how far the valve travels with .640 lift cams and hydraulic lifters. In my mind I'm thinking the lifters absorb part of that lift but then it's more than made up for by the longer valve push arm. I figure people with more experience probably have a cam lift to valve extension ratio that I could use.

Thanks for your thoughts.
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kouack
If your cam have an advertised 0,640 valve lift, it is what the valve will move if everything else is stock, especially your rocker arm. Stock Harley rocker arm have a 1,65 ratio. The lifters shall not take away any lift.

here a nice simple explanation
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Hoges
.640 valve lift.
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hillcat
Hoges said:
.640 valve lift.
Click to expand...
Correct as kouack said in his comment. ;)
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mcoolidge56
Thanks, the 1.65 ratio is good information. I just got my S&S 640 cams out of the engine and I only measure a .375 lift on the cam which translates to .619 valve opening. Now I know where I am. By the way that article was an interesting read.
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Don Dorfman
You should measure the cam lobe between centers with a travel indicator zero on the base circle. The rockers are 1.625:1 ratio to the best of my knowledge.
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