Valve springs
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Valve springs
How much life should I expect from a set of springs on a hi effort 900 + hp sbc wit .880” lift cam and should I back off valves when motor isn’t being run
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Re: Valve springs
Impossible to even come close with an answer ... What springs? How heavy is the vale train, (including the valve weight), and how aggressive is the camshaft for starters?rocketracer380 wrote: ↑Thu May 23, 2019 5:03 pm How much life should I expect from a set of springs on a hi effort 900 + hp sbc wit .880” lift cam and should I back off valves when motor isn’t being run
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Re: Valve springs
Spring quality is a huge factor, but if you were running some of the higher priced PAC, Isky or PSI parts, you could do worse than just regularly checking the seat loads and replacing the set when they've dropped 10% from the numbers seen after brief running from new.
A perhaps extreme example is a friend of mine that ran a $50 e bay set of Isky Tool Room™ springs in an 8,000 RPM 0.700" valve lift steel valve road race SBF for several years. They had lost less than 10# when he finally cycled them out.
Re backing off the valves for storage, opinions differ but mine is that you wouldn't do that when you parked your hyper car for the winter would you?
I keep telling myself I'll get around someday to selecting a couple of matched pairs of decent quality springs, squeezing half down to near-coil bind with a 1/2" nut and bolt and then comparing spring force every six months or so...
A perhaps extreme example is a friend of mine that ran a $50 e bay set of Isky Tool Room™ springs in an 8,000 RPM 0.700" valve lift steel valve road race SBF for several years. They had lost less than 10# when he finally cycled them out.
Re backing off the valves for storage, opinions differ but mine is that you wouldn't do that when you parked your hyper car for the winter would you?
I keep telling myself I'll get around someday to selecting a couple of matched pairs of decent quality springs, squeezing half down to near-coil bind with a 1/2" nut and bolt and then comparing spring force every six months or so...
Felix, qui potuit rerum cognscere causas.
Happy is he who can discover the cause of things.
Happy is he who can discover the cause of things.
Re: Valve springs
I'd be interested in how many cycles a spring like that could take before breaking when there are no "dynamic issues". It seems like something that manufacturers should be stating
Re: Valve springs
If the stress is low enough, spring life could be infinite...
Felix, qui potuit rerum cognscere causas.
Happy is he who can discover the cause of things.
Happy is he who can discover the cause of things.
Re: Valve springs
That's why I asked close to coil bind stress pretty damn high especially if the seat and nose loads are "high"
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Re: Valve springs
Madbill, i like your idea of that valve spring fatigue test-----find time to do it LOL, Mark H.
Re: Valve springs
Assuming well worked out geometry and no other herky issues.....the cam is the biggest factor in spring life.rocketracer380 wrote: ↑Thu May 23, 2019 5:03 pm How much life should I expect from a set of springs on a hi effort 900 + hp sbc wit .880” lift cam...
Re: Valve springs
Are valve springs similar to lifters in there are a few manufacturers and several distributors.
Recently had a set fail on the Dyno,4 pulls up to 65000 and at least 1/2 broke.
They were not pac or psi but we're a reputable name.
1.500 spring,795 lift 975 over the nose and .060-.065 to coil.
Strange part was a few broke in 3 pieces,like it had 1 coil removed.
No pattern,some here and some there.
Going to a 3 series pac next.
Recently had a set fail on the Dyno,4 pulls up to 65000 and at least 1/2 broke.
They were not pac or psi but we're a reputable name.
1.500 spring,795 lift 975 over the nose and .060-.065 to coil.
Strange part was a few broke in 3 pieces,like it had 1 coil removed.
No pattern,some here and some there.
Going to a 3 series pac next.
Re: Valve springs
Either something seriously wrong with the valvetrain, or some crazy harmonics going on. A close inspection and a completely different spring is not a bad idea. I don't know who actually manufacturers them, but Comp has those new dual conical springs that should be resistant to nutty harmonics. Just throwing that out there, as I have zero experience with them.Dutchman wrote: ↑Fri May 24, 2019 8:26 am Are valve springs similar to lifters in there are a few manufacturers and several distributors.
Recently had a set fail on the Dyno,4 pulls up to 65000 and at least 1/2 broke.
They were not pac or psi but we're a reputable name.
1.500 spring,795 lift 975 over the nose and .060-.065 to coil.
Strange part was a few broke in 3 pieces,like it had 1 coil removed.
No pattern,some here and some there.
Going to a 3 series pac next.
That being said, 65,000 rpm is really hard on stuff...
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Re: Valve springs
Did a little math. At 9000 RPM (each) valve spring cycles ( opens and closes ) 75 times per. second, 4500 times per minute, 270,000 times per hour at a constant 9000 rpm. Even in NASCAR you would have a lower than 9000 avg. , but one can work down from peak RPM and the numbers still add up fast. I always figured that the valve springs with less coils in them ( allowing for extreme lifts ) would take a beating and last for less cycles. I would almost bet the NASCAR teams put on NEW V-springs just before the actual race. Mark H. Forgot this>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
7500 RPM (avg.)
63 cycles per sec.
3750 per min.
225,000 per hour
3 hour race= 675,000 cycles per spring (OUCH)
If i made any mistakes let it be known !
7500 RPM (avg.)
63 cycles per sec.
3750 per min.
225,000 per hour
3 hour race= 675,000 cycles per spring (OUCH)
If i made any mistakes let it be known !
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Re: Valve springs
How should we define spring failure, by fatigue failure or compression set?
Fatigue failure is a function of number of cycles. This would include surge motion.
Compression set is when the spring is compressed beyond its elastic limit.
Given proper measurements and materials, both can be calculated.
Fatigue failure is a function of number of cycles. This would include surge motion.
Compression set is when the spring is compressed beyond its elastic limit.
Given proper measurements and materials, both can be calculated.
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Re: Valve springs
Valve springs and rod bolts. What is the life of these things? Important questions. Warp may have some cycles he could quote, but does it apply to your average bozo? I am certain that I change rod bolts way to soon, but I also have fire insurance on my house. The springs we can monitor. The set on my personal bracket sbc are well over 500 runs. They lost some right at the beginning, I added a little shim, they have been stable ever since. Makes me think twice about setting a 7500 rpm bracket motor too close to bind, no room to add shim. On the other hand, my circle track engines struggle to make it a season. Very application specific.
Re: Valve springs
Sorry to hijack this but....
One of the shops that does machine work for me is a WD on Kmotion springs. I've seen plenty of engines he's done and the springs seem to be pretty good.
I have Crower springs in my Mopar W-2 heads now. Around 145/425 on the seat/open pressure. They have been in those heads since 1994... Been stored under a shop bench except for about 40 laps. The original builder (different than the above shop) uses a ton of Crower parts.
I'm going to check these springs... Might use them might not.
Anyone else have much experience with Kmotion?
This is a sold flat tappet SBM. Around .550 lift ... 7,000 redline. Oval track. 3/8 2.02/1.60 valves. Ti retainers and 10 degree locks. Double springs with a damper
One of the shops that does machine work for me is a WD on Kmotion springs. I've seen plenty of engines he's done and the springs seem to be pretty good.
I have Crower springs in my Mopar W-2 heads now. Around 145/425 on the seat/open pressure. They have been in those heads since 1994... Been stored under a shop bench except for about 40 laps. The original builder (different than the above shop) uses a ton of Crower parts.
I'm going to check these springs... Might use them might not.
Anyone else have much experience with Kmotion?
This is a sold flat tappet SBM. Around .550 lift ... 7,000 redline. Oval track. 3/8 2.02/1.60 valves. Ti retainers and 10 degree locks. Double springs with a damper
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Re: Valve springs
This You Tube video got the two thumbs up from Scooter Brothers @ Comp Cams so might be of some help when selecting springs.
Enter this in Google or the YouTube search bar and you are there.
POWER TEC 10 EP 4 "New VALVE SPRING TEC leaked" no longer exclusive to top race engine builders
DV
Enter this in Google or the YouTube search bar and you are there.
POWER TEC 10 EP 4 "New VALVE SPRING TEC leaked" no longer exclusive to top race engine builders
DV
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