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header pipe length
rev, that is like the story of equal length headpipes on headers. building headers with unequal length headpipes spreads out the torque curve over a wider range -
Re: header pipe length
Yeah that's right BUT the point of the above is that anal retentive valve lash adjustment is a waste of time and according to Ron Iskenderian the P&G tool is a waste of money!
Dale.Comment
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Re: More On Valve Lash Adjustment
Actual running clearance is going to vary a few thou depending on engine operating mode. At idle the clearance will probably be about what you set it at cold, but hard running is going to tighten up the exhaust a bit, so adjusting valves to .0001" or even .0005" is not going to make any difference, and exhaust clearance ramps are typically greater to account for greater exhaust running clearance variation
If you get them within a thou, you're okay and a standard set of feeler gages will get you within less than a thou if you excercise reasonable care. My concern is that the valve is set down on the seat at no greater than ramp velocity, so you're better off to error a bit on the tight rather than the loose side, and I "factor" the specified clearance based on my actual measured rocker arm ratio, which means I set them a couple of thou tighter than spec. They will tend to loosen in service, so when you start hearing more valve train noise, it's time to check them again. The greater noise originates from the valves being set down on the seat at greater ramp velocity. If they are set down at ramp velocity, they should be quiet enough that you almost can't tell you have mechanical lifters.
"You'll make more power by setting them tight" is also a myth as a couple of thou one way or another is not going to make any significant difference in effective duration on a cam that has constant veloctiy ramps, but it MIGHT make a difference on a cam with constant acceleration ramps.
DukeComment
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my point was being perfect is not always right *NM*
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