Stage2 spring height & pressures
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- May 28, 2001
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I think..
you need more info.
The cam/lifter mfgr will specify the spring rate that should be used. Then, your spring choice will depend on the valve length, retainer spec, etc.
you need more info.
The cam/lifter mfgr will specify the spring rate that should be used. Then, your spring choice will depend on the valve length, retainer spec, etc.
turbodave231
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- May 24, 2001
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Spring height is also a function of valve length. the longer the valve, the taller valve spring. You need to pick valves based on length to keep the rocker contact patterns in the right place on the valve tip.
I just freshened my 0031 heads and I ended up with 1.920 spring installed height. I run a Ferrea valve(s) designed for Dart heads that are 5.460 long
What rockers are you using? I have seen that you can run longer valves with Jesel rockers versus T&D (or Crane). I beleive Jesels have a higher fulcrum point which allows for the longer valve (and therfore a taller spring installed height).
I found that I needed at least 300# on the seat. I have found that even mild cams need lots of spring pressure to keep the valves from floating. I ended up with a Comp Cams 1.625 OD triple spring and titanium retainer.
I just freshened my 0031 heads and I ended up with 1.920 spring installed height. I run a Ferrea valve(s) designed for Dart heads that are 5.460 long
What rockers are you using? I have seen that you can run longer valves with Jesel rockers versus T&D (or Crane). I beleive Jesels have a higher fulcrum point which allows for the longer valve (and therfore a taller spring installed height).
I found that I needed at least 300# on the seat. I have found that even mild cams need lots of spring pressure to keep the valves from floating. I ended up with a Comp Cams 1.625 OD triple spring and titanium retainer.
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- May 28, 2001
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here's some interesting dialog on springs...
U have to register to get to the advanced engine forum, but it's worth the effort..
Log inSpeed Talk
here's more:
http://www.network54.com/Forum/7418...esting++-+Heavier+943+Spring+on+the+Stock+Cam
U have to register to get to the advanced engine forum, but it's worth the effort..
Log inSpeed Talk
here's more:
http://www.network54.com/Forum/7418...esting++-+Heavier+943+Spring+on+the+Stock+Cam
turbodave231
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- May 24, 2001
- Messages
- 2,287
Great information!
Chuck,
A+++++++ Dude!
Some very interesting discussion and video in the links you provided. I have some similar video of a pushrod engine. Amazing to see the valve spring dance around like that!!
When I first built my S2 engine, my machinist was adamant that I didn't need the spring pressures over 200# on the seat. So I went with his recommendations. He didn't really have much experience with Forced induction engines. This was my first true "race" engine and I didn't have first hand experience......only the advice of those who had already been there.
The engine would pull hard to about 5500 RPM and then just lay down. In a handful of passes, I totally destroyed a set of adjusters in the new T&D rocker arms. It chewed up the tips on the pushrods, beat the rollers on the lifters and bent 6 exhaust valves. This was an expensive lesson to say the least!!
I've read alot of articles (David Reher) about higher spring rates. I was at first uncomfortable going with "battleship" valve springs. But now, I'm ok with whatever pressures it takes to control the valve. I can now see why engine builders like Reher and Morrison and Sonny Leonard use larger cam tunnels and large journal cams. They allow a larger core diameter on the cam......to avoid flex!!! My next engine will have roller cam bearings!!
I want to see what these guys discover about beehive valve springs!!!
Chuck,
A+++++++ Dude!
Some very interesting discussion and video in the links you provided. I have some similar video of a pushrod engine. Amazing to see the valve spring dance around like that!!
When I first built my S2 engine, my machinist was adamant that I didn't need the spring pressures over 200# on the seat. So I went with his recommendations. He didn't really have much experience with Forced induction engines. This was my first true "race" engine and I didn't have first hand experience......only the advice of those who had already been there.
The engine would pull hard to about 5500 RPM and then just lay down. In a handful of passes, I totally destroyed a set of adjusters in the new T&D rocker arms. It chewed up the tips on the pushrods, beat the rollers on the lifters and bent 6 exhaust valves. This was an expensive lesson to say the least!!
I've read alot of articles (David Reher) about higher spring rates. I was at first uncomfortable going with "battleship" valve springs. But now, I'm ok with whatever pressures it takes to control the valve. I can now see why engine builders like Reher and Morrison and Sonny Leonard use larger cam tunnels and large journal cams. They allow a larger core diameter on the cam......to avoid flex!!! My next engine will have roller cam bearings!!
I want to see what these guys discover about beehive valve springs!!!
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- May 28, 2001
- Messages
- 2,527
I can help with that....
The bee hive springs work well.
We have put them on stock iron heads, M&As and TA heads. I have not personally tried a set of Stage 2 heads but I dont see why they wont work.
Advanatages: 40 grams per valve less weight, use any cam with up to .650 lift above that Comp makes a bigger beehive that will work. The motor revs up much quicker and I have not seen any type of valve float on the dyno. We played with shift points up to 6900 with no problems on a cam designed for 6500.
Biggest advantage: I have not seen one wiped cam since using these springs and thats everything from stock to 1000 hp. There are about 8 or 9 motors here in CA using them so far.
The bee hive springs work well.
We have put them on stock iron heads, M&As and TA heads. I have not personally tried a set of Stage 2 heads but I dont see why they wont work.
Advanatages: 40 grams per valve less weight, use any cam with up to .650 lift above that Comp makes a bigger beehive that will work. The motor revs up much quicker and I have not seen any type of valve float on the dyno. We played with shift points up to 6900 with no problems on a cam designed for 6500.
Biggest advantage: I have not seen one wiped cam since using these springs and thats everything from stock to 1000 hp. There are about 8 or 9 motors here in CA using them so far.
