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Re: Valve lash kill and thrill [Re: BradH] #2723235
12/11/19 01:22 PM
12/11/19 01:22 PM
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central il.
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second 70 Offline
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central il.
Tighter makes it look like a bigger cam, loser makes it look smaller. correct?

Re: Valve lash kill and thrill [Re: BradH] #2723253
12/11/19 02:53 PM
12/11/19 02:53 PM
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northern,Ohio,USA
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Clanton Offline OP
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northern,Ohio,USA
BradH Thank you for your link and other input!I just wanted to be sure to say that.I changed my lash .008 tighter from .020 spec and will go back as a A B A test


GOTBOOST!New improved with Victor heads.
http://www.enginelabs.com/mopar-big-bloc...t-of-necessity/
Re: Valve lash kill and thrill [Re: second 70] #2723255
12/11/19 02:57 PM
12/11/19 02:57 PM
Joined: Jan 2003
Posts: 13,319
Marion, South Carolina [><]
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Marion, South Carolina [><]
Originally Posted by second 70
Tighter makes it look like a bigger cam, loser makes it look smaller. correct?

Yes. up


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
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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New York
polyspheric Offline
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New York
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
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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Bend,OR USA
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Cab_Burge Offline
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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 work That worked well on that motor up
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 shock shruggy


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Valve lash kill and thrill [Re: Cab_Burge] #2723677
12/13/19 10:47 AM
12/13/19 10:47 AM
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northern,Ohio,USA
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Clanton Offline OP
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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?


GOTBOOST!New improved with Victor heads.
http://www.enginelabs.com/mopar-big-bloc...t-of-necessity/
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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Posts: 15,439
Val-haul-ass... eventually
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BradH Offline
Taking time off to work on my car
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Val-haul-ass... eventually
Originally Posted by Clanton
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.

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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Posts: 4,309
Prospect, PA
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Prospect, PA
Originally Posted by BradH
Originally Posted by Clanton
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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