Re: Valve lash kill and thrill
[Re: Clanton]
#2722944
12/10/19 01:12 PM
12/10/19 01:12 PM
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Joined: Jul 2004
Posts: 19,317 State of confusion
Thumperdart
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I always tighten mine up .008-.010 just because and never an issue. As far as performance never compared back to back but make things quieter for sure....
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Valve lash kill and thrill
[Re: Thumperdart]
#2722945
12/10/19 01:18 PM
12/10/19 01:18 PM
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Joined: May 2011
Posts: 4,488 northern,Ohio,USA
Clanton
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Interesting info.That is a lot to tighten up when the spec may only be .020 I always tighten mine up .008-.010 just because and never an issue. As far as performance never compared back to back but make things quieter for sure....
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Re: Valve lash kill and thrill
[Re: Clanton]
#2722956
12/10/19 01:45 PM
12/10/19 01:45 PM
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Joined: Jan 2003
Posts: 13,319 Marion, South Carolina [><]
an8sec70cuda
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On my hemi I used to run the lash a little looser than recommended. Felt a little snappier to me w/ it .003" on the loose side. Whether it made any difference on the timeslip or not, I don't know.
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]
#2722957
12/10/19 01:46 PM
12/10/19 01:46 PM
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Joined: Feb 2005
Posts: 20,116 PA.
pittsburghracer
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Interesting info.That is a lot to tighten up when the spec may only be .020 I always tighten mine up .008-.010 just because and never an issue. As far as performance never compared back to back but make things quieter for sure.... .020 is a tight spec for most cams. If I remember right I ended up at .008 COLD on my Keith Black block and 440-1 heads. Lots of growth with that combo but I'm usually at .008-.010 like thumper said with a cast iron block and aluminum heads.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Valve lash kill and thrill
[Re: Clanton]
#2722968
12/10/19 02:11 PM
12/10/19 02:11 PM
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Joined: Aug 2003
Posts: 43,007 Bend,OR USA
Cab_Burge
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Bend,OR USA
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Tight lash cams, .020 or tighter when hot, can not be ran safely with NO more than 25% tighter lash when hot. I use the old rule that if the motor likes less lash at the track on back to back runs then it needs a bigger camshaft I've seen tighter lash work better as well as not working as good on engines on the dyno and at the track also, it depends on the combination normally
Last edited by Cab_Burge; 12/10/19 06:54 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Valve lash kill and thrill
[Re: Cab_Burge]
#2722990
12/10/19 02:54 PM
12/10/19 02:54 PM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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Cams that use tighter design lash, and/or faster ramps have less of a lash tuning window before you start compromising durability.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Valve lash kill and thrill
[Re: fast68plymouth]
#2723002
12/10/19 03:29 PM
12/10/19 03:29 PM
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Joined: Jun 2006
Posts: 5,155 CT
GTX MATT
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I have noticed a difference with as little as .002. Not huge, but could feel it. And .004 loose was worth 10 PSI cranking compression and an inch of vacuum on one combination. You're not supposed to go much looser than the spec, I've heard .002 is OK for most, some might tolerate more.
My understanding is tighter is not an issue as long as its closing and there is some lash. Although every .001 tighter you go is going to add more duration than the last .001. The slower the lobe the more the lash is going to effect it (more duration for every .001)
Now I need to pin those needles, got to feel that heat Hear my motor screamin while I'm tearin up the street
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Re: Valve lash kill and thrill
[Re: fast68plymouth]
#2723003
12/10/19 03:30 PM
12/10/19 03:30 PM
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Joined: May 2011
Posts: 4,488 northern,Ohio,USA
Clanton
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What would make a fast ramp rate? .003 or .006 lift per cam degree? Cams that use tighter design lash, and/or faster ramps have less of a lash tuning window before you start compromising durability.
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Re: Valve lash kill and thrill
[Re: Clanton]
#2723006
12/10/19 03:44 PM
12/10/19 03:44 PM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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More change in lift per degree would be “faster”.
And some lobes just have smoother transitions from one portion of the lobe to another, even if the peak velocities are nearly the same.
This is where it’s best to be able to talk with someone at the cam supplier who understands those minute differences between the lobe families....... and what kind of affect it may have on your combo.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Valve lash kill and thrill
[Re: Clanton]
#2723013
12/10/19 04:06 PM
12/10/19 04:06 PM
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Clanton
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I see on google that a .050 lift gain from .006 to .050 lift would be a fast ramp rate. and .030 an avg ramp;slower]
or An exapme of a fast ramp cam would be an Ultradyne Cam it had a 276int/276ex for advertised duration and the duration @.050 was 221int/221ex. This is a fairly fast ramp for a hydraulic lifter cam.
Last edited by Clanton; 12/10/19 04:19 PM.
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Re: Valve lash kill and thrill
[Re: Clanton]
#2723030
12/10/19 04:58 PM
12/10/19 04:58 PM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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That’s a hyd cam..... and imo, not a very fast one @55* “hydraulic intensity”.
The lower the number/difference between .006 and .050, the higher the intensity.
The Comp XE/HL lobes have 44* hyd intensity(275@.006>231@.050). The normal XE lobes are usually in the 44* range as well(268@.006>224@.050).
Even most of the old school HE and Magnum cams are 50* or less. (270@.006>224@.050 = 46*) (280@.006>230@.050 = 50*)
The Thumper intake lobes are 52* hyd intensity, but the ex lobes are slower with 56* hyd intensity.
Some of the Lunati VooDoo cams are 43* hyd intensity.
Although pretty much every cam lobe design is a compromise of some sort.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Valve lash kill and thrill
[Re: fast68plymouth]
#2723070
12/10/19 07:54 PM
12/10/19 07:54 PM
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Joined: May 2011
Posts: 4,488 northern,Ohio,USA
Clanton
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Thanks a ton for clearing that up! That’s a hyd cam..... and imo, not a very fast one @55* “hydraulic intensity”.
The lower the number/difference between .006 and .050, the higher the intensity.
The Comp XE/HL lobes have 44* hyd intensity(275@.006>231@.050). The normal XE lobes are usually in the 44* range as well(268@.006>224@.050).
Even most of the old school HE and Magnum cams are 50* or less. (270@.006>224@.050 = 46*) (280@.006>230@.050 = 50*)
The Thumper intake lobes are 52* hyd intensity, but the ex lobes are slower with 56* hyd intensity.
Some of the Lunati VooDoo cams are 43* hyd intensity.
Although pretty much every cam lobe design is a compromise of some sort.
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Re: Valve lash kill and thrill
[Re: Clanton]
#2723075
12/10/19 08:09 PM
12/10/19 08:09 PM
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Joined: Jan 2003
Posts: 14,479 So. Burlington, Vt.
fast68plymouth
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Of course, none of that has anything to do with “lash”.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Valve lash kill and thrill
[Re: fast68plymouth]
#2723085
12/10/19 09:16 PM
12/10/19 09:16 PM
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Joined: May 2011
Posts: 4,488 northern,Ohio,USA
Clanton
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I see a lot of people increasing lash to adjust for having too much duration trying to be street strip,pump gas so is the down side only having more valve noise?A SFT would be more at risk of dammage I would think. Of course, none of that has anything to do with “lash”.
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Re: Valve lash kill and thrill
[Re: GTX MATT]
#2723105
12/10/19 10:33 PM
12/10/19 10:33 PM
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Joined: Jul 2006
Posts: 4,319 Puyallup, WA
StealthWedge67
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I have noticed a difference with as little as .002. Not huge, but could feel it. 😳
LemonWedge - Street heavy / Strip ready - 11.07 @ 120
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Re: Valve lash kill and thrill
[Re: StealthWedge67]
#2723177
12/11/19 09:09 AM
12/11/19 09:09 AM
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Joined: Jan 2003
Posts: 8,005 Tulsa OK
Bad340fish
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I have noticed a difference with as little as .002. Not huge, but could feel it. 😳 Hey we have all done things to our car that satisfy the butt dyno feeling, but fail to produce on the time slip.
Last edited by Bad340fish; 12/11/19 10:50 AM.
68 Barracuda Formula S 340 87 "Chrysler" Conquest
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Re: Valve lash kill and thrill
[Re: Bad340fish]
#2723195
12/11/19 10:29 AM
12/11/19 10:29 AM
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Joined: Jun 2006
Posts: 5,155 CT
GTX MATT
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You can believe it or not, but you're moving the valve open and closing points slightly. The engine idled 50-75 RPM higher and was just a little more crisp without touching anything else. It's like moving your cam timing a half or 1 degree.
Now I need to pin those needles, got to feel that heat Hear my motor screamin while I'm tearin up the street
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Re: Valve lash kill and thrill
[Re: GTX MATT]
#2723228
12/11/19 01:07 PM
12/11/19 01:07 PM
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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
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Val-haul-ass... eventually
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IIRC, most cam companies suggest making lash changes for testing in .004" steps (assuming the lash ramp allows for that much range of adjustment); .002" makes a difference, but not much of one. That's part of why I posted the link above, in order to quantify some actual at-the-valve duration changes resulting from the different tests referenced.
Tell four different people to set the lash to .018" on the same engine and you could end up w/ actual lash ranging from .016" to .020" simply because of the variations in their technique.
For engine dyno testing, I believe that repeatability within 1% is considered very good. But that's still saying that if pull #1 made 600 HP and pull #2 made 606 HP w/ absolutely no changes between them, they're still considered to have "repeated". I doubt a lash change of .002" can be validated w/in a 1% variance, even if there is some other characteristics that change as a result (e.g., if you can A-B-A test an idle speed increase).
Last edited by BradH; 12/11/19 01:30 PM.
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