Re: Valve lash hot vs cold
[Re: The Sphinx]
#2511902
06/22/18 09:05 PM
06/22/18 09:05 PM
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crabman173
Unregistered
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crabman173
Unregistered
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Set it to .020 to .022 range fire it up--after it is hot go over the lash--set to correct specs -- always set your lash hot from then on No matter where you set it cold for that first run it will be fine no worry In the future any cam you don't know the specs set to .022 cold and never look back it will run fine Good Luck
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2511910
06/22/18 09:30 PM
06/22/18 09:30 PM
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Joined: Oct 2007
Posts: 4,209 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,209
New York
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What matters: NO MATTER WHAT you do not have negative lash at any temperature. Even zero is safe until you keep the valve open even that tiniest little bit.
Boffin Emeritus
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Re: Valve lash hot vs cold
[Re: dvw]
#2511918
06/22/18 09:53 PM
06/22/18 09:53 PM
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Joined: Jan 2007
Posts: 7,664 IN
ahy
master
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master
Joined: Jan 2007
Posts: 7,664
IN
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I never set mine hot. With aluminum heads set the int .006"/ exh .005" tighter cold than the hot spec. Warm it up and measure a few intakes and exhausts. Recheck those same valves after it sets overnight. How far did they change from the measured hot setting to the current measurement? Then do the math of the change. Now when you set them cold they'll be where you want hot. Doug This works for me. Also agree, a little loose on break in will not hurt.
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2511925
06/22/18 10:10 PM
06/22/18 10:10 PM
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Joined: Dec 2004
Posts: 10,555 Rittman Ohio
fourgearsavoy
I Live Here
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I Live Here
Joined: Dec 2004
Posts: 10,555
Rittman Ohio
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I always set mine at .016-.018 dead cold. Not a big fan of setting them hot unless you use a temperature probe and set them the same every time. I really don't understand why some cams spec at anything wider than .020 Can somebody enlighten me? Gus
64 Plymouth Savoy 493 Indy EZ's by Nick at Compu-Flow 5-Speed Richmond faceplate Liberty box Dana 60
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2511949
06/22/18 11:07 PM
06/22/18 11:07 PM
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Joined: Sep 2015
Posts: 1,096 Australia
ozymaxwedge
super stock
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super stock
Joined: Sep 2015
Posts: 1,096
Australia
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Reassuring, I have just set mine cold at 16, I will check them again after 20 miles or so and I'll be setting them cold.
1963 Plymouth Max Wedge 1971 Barracuda
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2511970
06/22/18 11:34 PM
06/22/18 11:34 PM
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Joined: Dec 2005
Posts: 11,608 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,608
Fulton County, PA
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As per Comp
"All COMP Cams® valve lash settings are “hot” settings (intended to be set at normal engine operating temperature), but will work for initial start-up as well."
How I've always done it. I don't run it for an hour. Just put some heat in. Maybe 150, that's around where I come out of the lanes. Have to be organized so you don't take all afternoon to do it.
If the results don't match the theory, change the theory.
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2511979
06/22/18 11:46 PM
06/22/18 11:46 PM
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Joined: Aug 2003
Posts: 43,223 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,223
Bend,OR USA
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Last edited by Cab_Burge; 06/22/18 11:47 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2512044
06/23/18 03:21 AM
06/23/18 03:21 AM
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Joined: Jul 2006
Posts: 4,319 Puyallup, WA
StealthWedge67
master
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master
Joined: Jul 2006
Posts: 4,319
Puyallup, WA
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My cam calls for .018 & .020. I set Them cold at .013 & .015; Ive found them typically on the tight side of the spec numbers when checked warm.
LemonWedge - Street heavy / Strip ready - 11.07 @ 120
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2512123
06/23/18 12:17 PM
06/23/18 12:17 PM
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crabman173
Unregistered
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crabman173
Unregistered
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Real race engine builders know and understand that initial start up--It does not matter as long as you have some lash OK? But they also know that if you understand Anything about an engine or racing or cams or this business that you set valves hot Period! That is IF you want it right--so since that thing will run with about any setting folks start getting cute and come up with all this BS calculations etc from cold to hot etc and decide they know more than the engineers that designed the engine and or parts Well...you don;t--you get a pass because the engine will run with the valves open a little or with .040 lash so you wind up thinking you are on to something--you are--Not following age old guidelines that are designed to help you get it Correct
In the past i used some Cam motion cams that were inverse radius designs--the low spot on the lobe was NOT on the base it was up the side--so setting valves was tricky--I remember a 500 CI big block that was running 5.10's after delivery then a couple weeks later was winning rounds but running 5.40's owner had set valves WAY too tight and valves were not closing--we re-set lash and it went right back to 5.10's no harm done OK you set them at .040 and guess what ??It runs but sounds like two skeletons screwing on a tin roof--yes it can and will harm the unit by bashing the lifters but my point is IF you want to know something about this subject just follow the CORRECT procedure for setting mechanical lash and do it HOT or ...produce your engineering degree thesis you did on why your way is "better"
Gees! This is an easy subject that gets lots of argument from people that just will not listen
I believe that the reason for that I have already stated --an engine will run with almost any lash but each lobe design has very specific lash settings based on lifter diameter and opening and closing ramp designs as well as many other factors so WHY fight the engineers that built the part??????????
OK you set it correctly HOT and then check when cold so you have an idea --makes life easier I get that but honestly please just derive that info from a HOT setting will ya?
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2512132
06/23/18 12:37 PM
06/23/18 12:37 PM
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Joined: Oct 2007
Posts: 4,209 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,209
New York
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If a valve does not close that cylinder is out.
Boffin Emeritus
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Re: Valve lash hot vs cold
[Re: polyspheric]
#2512151
06/23/18 01:18 PM
06/23/18 01:18 PM
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crabman173
Unregistered
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crabman173
Unregistered
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Right but even with some negative lash and valve not closed tight tight a rookie will not know except when looking at ET slip based on my personal observations in that one case Theory and answers it takes to get an 'A" on the test are not always dead on except on paper For sure it is awful to run like that and has all kinds of consequences but ...... That tale was to aid in enlightenment and flesh out my entire argument
I greatly respect your knowledge--- I try and help where I can adding in real world experiences--reading a book about how to swim is a good start but you can't read that book and jump off a pier or you will go to the bottom--
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Re: Valve lash hot vs cold
[Re: dvw]
#2512168
06/23/18 02:04 PM
06/23/18 02:04 PM
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crabman173
Unregistered
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crabman173
Unregistered
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Right! Base it off the Hot reading
I set mine just like you are thinking but always always based on Hot reading
Hot is full engine temp like 5-10 minutes after a run Yea it ain't fun but then you know what it really is
FWIW after the first few times they all should settle down and you don't need to get in there but every so often just to check--I like to keep after them so I catch a lifter wheel or lobe getting into trouble before it gets to Code Red
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2512249
06/23/18 05:31 PM
06/23/18 05:31 PM
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Joined: Dec 2005
Posts: 11,608 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,608
Fulton County, PA
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Why don't you want heat in the engine? Burn your fingers? Gas expensive? Why do engine builders use deck plates and run hot water through the block when boring & honing? Cam manufacturer says HOT. My junk is 140-150 going into the water, not 70. I just going to warm it up, let it heat soak for a few minutes and run the valves. Then I know and not guessing.
If the results don't match the theory, change the theory.
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Re: Valve lash hot vs cold
[Re: The Sphinx]
#2512424
06/24/18 01:01 AM
06/24/18 01:01 AM
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Joined: Dec 2005
Posts: 11,608 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,608
Fulton County, PA
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It's my routine. Always has been. Doing it someone else's way may work fine. Never said it was wrong. I don't typically open the engine up at the track. This is shop maintenance. Once a fresh engine has settled down, I don't do it every week. Warm it up, throw a light on it to make sure nothing has moved. Check the trans. Run the valves. Look everything over. I can do the valves in a few minutes if nothing's out of whack. Upside? IDK. Taking care of all this at once. No fudge factors to forget.
If the results don't match the theory, change the theory.
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