cam removal without removing pushrods
Ultimate HDF Member
Joined: Jan 2008
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From: SoCal
I think what he is saying is if all the components stack up to make the cylinder head taller than the average there is a possibility that the pr's would be too short. Possibly not pushing the valve down to the advertised specs. If they were within what the hyd lifter can compensate for it may not be an issue. But if by chance all the stacking works against you, ie tall head, tall rocker box, tall cylinder, short pr's, etc this is a possibility. I know how they are supposed to match parts on an assembly line but it could happen.
Elite HDF Member
Joined: Aug 2010
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From: Mpls, MN
Could you explain the sentence of your post that I have bolded?
Unless the pushrods are grossly undersized (to the point of still having lash at maximum lifter extension) there is no effect on either lift or duration. Lift and duration are governed by the cam grind and cannot be altered by pushrod length.
Unless the pushrods are grossly undersized (to the point of still having lash at maximum lifter extension) there is no effect on either lift or duration. Lift and duration are governed by the cam grind and cannot be altered by pushrod length.
You sure?
I'd think push rod length/clearance would effect both valve timing and lift.
Al
Elite HDF Member
Joined: Nov 2010
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From: Simi Valley, CA
Yep! I'm sure. Like I said in my previous post, unless the pushrod is grossly undersize to the point of lash in the system it will not have any effect on lift or duration. The lifters have about .200" of travel in them so that leaves a substantial range for acceptable pushrod length.
Elite HDF Member
Joined: Nov 2010
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From: Simi Valley, CA
And I agree that changing valve lash will alter timing and lift - BUT - in a hydraulic lifter system there is no lash (or at least there shouldn't be).
Elite HDF Member
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From: Mpls, MN
Stellar HDF Member
Joined: Aug 2012
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From: Indiana, USA
I believe all lifters have a sweet spot and yes by design there is a range they will operate however, I do know that I can adjust pushrods and have a hydraulic lifter tick and I can adjust pushrods and not have a tick. I also believe that a cold engine may not tick when a hot engine will. keep in mind the coeffecient of thermal expansion in the aluminum components will generate significant increase in the height of the overall assembly as the engine warms to operating temperature. I believe when I have a tick the hydraulic lifter is not compensating for lash therefore tick= lash = less than full utilization of the cam profile.
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