Re: Valve lash kill and thrill
[Re: second 70]
#2723255
12/11/19 02:57 PM
12/11/19 02:57 PM
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Joined: Jan 2003
Posts: 13,385 Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,385
Marion, South Carolina [><]
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Tighter makes it look like a bigger cam, loser makes it look smaller. correct? Yes.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
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Re: Valve lash kill and thrill
[Re: Clanton]
#2723261
12/11/19 03:33 PM
12/11/19 03:33 PM
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Joined: Oct 2007
Posts: 4,210 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,210
New York
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There are of course limits. Too loose will destroy the parts, the tappet is not the only location of slack. Too tight is only dangerous one way: the valve does not close. A valve left open .002" stops working, and says so (DV).
Boffin Emeritus
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Re: Valve lash kill and thrill
[Re: polyspheric]
#2723298
12/11/19 05:51 PM
12/11/19 05:51 PM
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Joined: Aug 2003
Posts: 43,285 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,285
Bend,OR USA
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I've own and driven a V.W powered sand rail for a lot of years, I ended up buying motor parts from several different off road racers in SO CA to make it faster. In the process I learned from them that all air cool V.W. motor have solid lifters and the factory spec of setting the lash cold at .0040 was to loose, those racers suggested setting them at .0000 or just tight enough to be able to still rotate the pushrod by hand , but not easily, just barely able with two fingers to rotate them at outside air temps when cold That worked well on that motor I did find out on my last pump gas motor with a set of Harland Sharp 1.65 ratio single shaft rocker arms that combination of parts on that motor the lash would only change by .0010 from room temps to 180F
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Valve lash kill and thrill
[Re: Clanton]
#2723680
12/13/19 10:52 AM
12/13/19 10:52 AM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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I have read that a .010 tighter lash was equal to 1pt in compression less for someone trying to adjust for lower octane so would a looser lash be a gain in 1pt cr? That statement makes far too many assumptions for me to put any faith in it, regardless of the source.
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Re: Valve lash kill and thrill
[Re: BradH]
#2723847
12/13/19 09:04 PM
12/13/19 09:04 PM
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Joined: Feb 2005
Posts: 4,318 Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,318
Prospect, PA
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I have read that a .010 tighter lash was equal to 1pt in compression less for someone trying to adjust for lower octane so would a looser lash be a gain in 1pt cr? That statement makes far too many assumptions for me to put any faith in it, regardless of the source. Right. And what "compression"? I guess because were adjusting valve timing with lash adjustments, it must mean dynamic "compression". And of course the collective "we" cannot even agree on exactly what valve position we should use to calculate dynamic compression. All that said, I cannot see it changing dynamic compression 1 pt. I do know that my motor will blow 5 psi more with 0.004-5" lash added.
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