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Valve springs: Why must they be compressed down to .050 ? #2255070
02/17/17 04:01 PM
02/17/17 04:01 PM
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Washington
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hemienvy Offline OP
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hemienvy  Offline OP
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Help me understand something.

I can see that "spring surge" is bad. (the Slinky effect)
I always thought that the inner spring(s) or the spring
damper controlled spring surge.
Not sure if "spring surge" = "spring harmonics".

Anyway, I keep reading that it is best practice to set up
the springs to be compressed down to .050" off of coil bind
at max lift.

Why ?

I would think that the less you compress a spring, the less
stressed the metal is. So, this would mean that at max lift,
you would want to be much farther from coil bind, .300~~.400
or more.

What am I missing ?

Re: Valve springs: Why must they be compressed down to .050 ? [Re: hemienvy] #2255081
02/17/17 04:17 PM
02/17/17 04:17 PM
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Bend,OR USA
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Cab_Burge Offline
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Originally Posted By hemienvy

What am I missing ?

Research and development by racers and race valve spring companies work shruggy
I've been told by several different cam companies to shoot for between .060 to .080 from coil bind on any solid roller valve springs, I've used those suggestions for years now up
Some things that we justify in our minds, especially on race parts, don't make it true shruggy
Spurgoen Goins years ago, who owned AFR at that time , told me to compress every valve spring within .100 of coil bind in a vice and let it sit for at least 4 hrs. to allow the spring to "normalized" He was doing contract work for GM and Jr. Johnsons NASCAR team on the valve train and cylinder heads at that time up

Last edited by Cab_Burge; 02/17/17 04:21 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Valve springs: Why must they be compressed down to .050 ? [Re: Cab_Burge] #2256722
02/20/17 06:00 PM
02/20/17 06:00 PM
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hemienvy Offline OP
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Thanks, Cab.

OK, one and only post bump here.

I can't believe more people are not interested in this.
It affects everyone ! Calling on engineers.....

Re: Valve springs: Why must they be compressed down to .050 ? [Re: hemienvy] #2256772
02/20/17 08:02 PM
02/20/17 08:02 PM
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Engineers deal with theory, racers deal with reality and actual in the field results work stirthepot
BTW, I have a degree in electronics. I've also drag raced and won races at the dragstrip since 1964 whistling grin shruggy


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Valve springs: Why must they be compressed down to .050 ? [Re: hemienvy] #2256842
02/20/17 09:59 PM
02/20/17 09:59 PM
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State of confusion
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As stated, new tech and lots of development have determined the closer to coil bind not the farther away the better..........iirc mine are around .060-.070 w/a solid roller and 7000+ rpm's for years street/strip.......... thumbs


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.....
Re: Valve springs: Why must they be compressed down to .050 ? [Re: hemienvy] #2256861
02/20/17 10:31 PM
02/20/17 10:31 PM
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DaveRS23 Offline
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I have always heard that spring failure rates go way up as you get into that last little bit before bind due mostly to much higher heat build up and, of course, stress.

Any truth to that?


Master, again and still
Re: Valve springs: Why must they be compressed down to .050 ? [Re: hemienvy] #2256907
02/21/17 12:01 AM
02/21/17 12:01 AM

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crabman173
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In class where you want an A you answer get springs set up to near 050 from coil bind
In the REAL world nothing could be farther from the way it usually happens
Think about Dart for example--they sell thousands of heads with springs that will work well with a wide range of lifts up to a certain lift--so does Edelbrock etc
So you are never at that magic number
Take a set of heads to a REAL RACE shop and spend big $$--or have them build you a serious race only unit and..guess what? you get the springs ( usually high quality PAC or others) set up exactly on the edge of about 050 to 060 from coil bind
Do that at home and get trouble--you FORGET to check the all important inner didn't you? and IT is the one that binds and friggs everything up--and you were aimin to impress by getting it " like the big boys do" right? Whew!! Big mistake for home builders!!!!!
I have built hundreds an hundreds of race engines that had all kinds of room to coil bind--with a GOOD driver they win races and don't fail!!
Valve springs usually fail for several plain boring reasons

#1 Tool steel they don't lose pressure--but...those darn things break!
A failed spring is a tool steel spring--ever wonder why there are millions of sets of high dollar springs on Ebay cheap--they run them ONE race and toss them so they don't break
#2 Interference--something is banging into something else--simple--you did not build it right and do not know what the heck you are doing
#3 They floated because you rev'd them beyond the limits of the cam/lobe design/part used/ etc You again--screwed up and maybe don't know how to drive a RACE car
#4 they did not have enough pressure to control your "dumb azz custom cam" that you should have had an engine builder spec out instead of the 4 week guy at COMP ( try Bullit or Jim at Racer Brown or Cam Motion and keep on winning)
#5 valve train is HEAVY ( because it is a Mopar) and again you do not have enough spring to control that fat girlfriend of a cam lobe spec'd by a damn computer that has never raced anybody
#6 you failed to use Titanium retainers--if you did not use them you do not know what you are doing--repeat this several times before you go to bed tonight
Silicon springs do lose a little pressure but they never break unless you bang then into something else Me likey!!!

Re: Valve springs: Why must they be compressed down to .050 ? [Re: ] #2256993
02/21/17 02:35 AM
02/21/17 02:35 AM
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I set my heads up with the springs, retainers and keepers that will go on that valve one at a time. I have a older Rimac 1000 lb. valve spring tester that I use to set the springs up on,I do not set them all up to the same specs. tsk
I have hardened valve springs shims in .015, .030 and .060, I also measure all of them as I use them. I see around .004 t0 .006 variance in the shim thickness shruggy
I use lightweight checking springs to check the piston to valve clearances, intake lobe timing as well as the lift at the retainers to verify the rocker arm ratio at the retainers. I see from .015 to .020 loss of lift with the race springs on the heads compared to the checking springs shruggy
That ends up making them have from .070 to around .090 clearances on the springs from coil bind, I do that with the thought that the aluminum heads will get from .003 to .012 taller when warmed up racing it than the length of the steel valve stem will grow when hot work shruggy
Lots of variables out there for Murphy to use to mess with us racers and engine builders whistling grin

Last edited by Cab_Burge; 02/21/17 02:39 AM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Valve springs: Why must they be compressed down to .050 ? [Re: Cab_Burge] #2257001
02/21/17 03:15 AM
02/21/17 03:15 AM
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Melbourne , Australia
LA360 Offline
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Basically anyone who built Comp Eliminator or Super Stock engines that I've dealt with usually runs their springs closer to bind than 0.040"-0.050"
Many go to around 0.020" or there abouts


Alan Jones
Re: Valve springs: Why must they be compressed down to .050 ? [Re: LA360] #2258357
02/23/17 10:04 PM
02/23/17 10:04 PM
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dogdays Offline
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To the OP: Because they work better that way.

How do we know? Spend enough hours with a Spintron and you'll see it too. It's ironic because growing up it was "Keep the spring away from coil bind, 0.060" is as tight as you should ever be." I bet you could find 100 examples of that thinking in magazines and books and catalogs.

The other thing is it is very much rpm-related. So for a street engine that is never going to see over 5000 rpm I'd think it was much less important.

R.

Re: Valve springs: Why must they be compressed down to .050 ? [Re: hemienvy] #2258643
02/24/17 12:26 PM
02/24/17 12:26 PM
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New York
polyspheric Offline
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And the way we know that every individual coil compresses at the same rate, at the same time, so they never touch and generate a shock wave is...?


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