Single beehive vs dual spring
03-17-2011, 02:37 PM
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Single beehive vs dual spring Which would be better for a higher reving car and why? Single or dual valve spring?
They only reason I am asking is because I have a cam with .609 max lift and the new 918s are good up to .625.
Which would be better for a .609 max lift cam thats willo rev to 6.8k?
The reason I am asking is becasue its about a 100 dollar price difference
They only reason I am asking is because I have a cam with .609 max lift and the new 918s are good up to .625.
Which would be better for a .609 max lift cam thats willo rev to 6.8k?
The reason I am asking is becasue its about a 100 dollar price difference
03-17-2011, 03:01 PM
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Granted both can break doesn't matter how much they are. There is a rather large sticky about springs. But I was directed towards dual from a few sources/shops. The patriotgold dual. The cam i purchased with not see that much lift either compared to qhat you just mentioned
03-17-2011, 05:23 PM
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I don't think he necessarily meant that one is more or less prone to mechanical failure. If one of the dual springs breaks, the other one will prevent the valve from being completely dropped and potentially causing significant harm to your engine/heads. If a beehive single spring breaks, there is no additional safety net to keep the valve from crashing the combustion chamber party.
If I'm wrong, someone feel free to correct me
If I'm wrong, someone feel free to correct me
03-17-2011, 05:26 PM
#6
Beehives don't have a back up spring.
Exactly!
I don't think he necessarily meant that one is more or less prone to mechanical failure. If one of the dual springs breaks, the other one will prevent the valve from being completely dropped and potentially causing significant harm to your engine/heads. If a beehive single spring breaks, there is no additional safety net to keep the valve from crashing the combustion chamber party.
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03-17-2011, 07:19 PM
#9
The current 918s are a much higher rate than the original 918s. Too high for my liking. But being beehives, they have one ultimate advantage over any and all dual springs: They can't ever have spring-surge. Thus you never get spring-surge-caused dips in the torque curve, especially at higher rpm. That surely must over-rule every other consideration.
Duals providing a backup is a false notion. If you need the rate of duals for high rpm, (1) if you break the outer, then the inner alone won't be enough to keep the piston from kissing the valve, and (2) most of the extra rate is lost on the extra spring mass and the much larger retainer.
Dual springs are 1960s tech. Ancient, out-dated, obsolete.
If you want something more than the 918, well, COMP makes beehives intended for the BBC, any good machine shop can help you use those.
Duals providing a backup is a false notion. If you need the rate of duals for high rpm, (1) if you break the outer, then the inner alone won't be enough to keep the piston from kissing the valve, and (2) most of the extra rate is lost on the extra spring mass and the much larger retainer.
Dual springs are 1960s tech. Ancient, out-dated, obsolete.
If you want something more than the 918, well, COMP makes beehives intended for the BBC, any good machine shop can help you use those.
03-17-2011, 09:04 PM
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The current 918s are a much higher rate than the original 918s. Too high for my liking. But being beehives, they have one ultimate advantage over any and all dual springs: They can't ever have spring-surge. Thus you never get spring-surge-caused dips in the torque curve, especially at higher rpm. That surely must over-rule every other consideration.
Duals providing a backup is a false notion. If you need the rate of duals for high rpm, (1) if you break the outer, then the inner alone won't be enough to keep the piston from kissing the valve, and (2) most of the extra rate is lost on the extra spring mass and the much larger retainer.
Dual springs are 1960s tech. Ancient, out-dated, obsolete. If you want something more than the 918, well, COMP makes beehives intended for the BBC, any good machine shop can help you use those.
Duals providing a backup is a false notion. If you need the rate of duals for high rpm, (1) if you break the outer, then the inner alone won't be enough to keep the piston from kissing the valve, and (2) most of the extra rate is lost on the extra spring mass and the much larger retainer.
Dual springs are 1960s tech. Ancient, out-dated, obsolete. If you want something more than the 918, well, COMP makes beehives intended for the BBC, any good machine shop can help you use those.
My cam requires a springs that has 150lbs on the seat, a rate of 500lbs/inch and handles a .621" lift.
What comp beehive should I use?
03-17-2011, 10:42 PM
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Actually I went with the torquer v2 .595/.598 lift and even though the 918's (PAC or Comp) are rated to .625, the safety range is .600.
I read about a problem they had with Comp 918's. Several had broken, maybe less than 20 instances on all different types of engines and Comp had taken care of every claim. Never said they fixed the problem, still being manufacted down in Mexico as far as I know. Which is where they went after PAC quit making Comp's 918's.
Because I did not trust the .600 safe range, even though I could say it would hold .625 I went with an option Texas Speed had for a single behive that was rated safely at .650 lift. It is made by PAC but I don't know the part number. I checked every single spring rate and they were dead on. I'm very happy, they are installed on the heads now and waiting to get this project done.
So to answer your question ^ maybe not a Comp beehive but a PAC .650 beehive may be your answer?
...just received them yesterday...very nice kit indeed 
03-19-2011, 12:14 PM
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go with what the cam company recommends,whether it's a dual or single beehive.
both types of springs have their place.
a dual spring isn't necessarily "safer" than a single beehive.you can drop a valve just as easily with duals.the second,inner spring should never be considered a "backup"to the outer spring,that was never it's intended purpose.
more importantly is setting up the valvetrain properly(proper spring height,seated pressures,etc.)
both types of springs have their place.
a dual spring isn't necessarily "safer" than a single beehive.you can drop a valve just as easily with duals.the second,inner spring should never be considered a "backup"to the outer spring,that was never it's intended purpose.
more importantly is setting up the valvetrain properly(proper spring height,seated pressures,etc.)
03-19-2011, 12:39 PM
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Duals all the way. Here is what a single spring looks like when it fails. Mine failed while autoxing just as I crossed the finish line. I got lucky because the valve didn't drop and there was no collateral/catostrophic damage.
Next set springs were duals, no doubts. And don't go cheap seats either. Do the homework and get a quality set of duals that meet your needs, not the flavor of the month.
Next set springs were duals, no doubts. And don't go cheap seats either. Do the homework and get a quality set of duals that meet your needs, not the flavor of the month.
