FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: plovett on August 20, 2020, 06:25:17 AM
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If you have a dual pattern cam with different max valve lifts do you shim the side with the lower valve lift to get about the same open pressure?
Often, but not always the exhaust has more lift and so more open pressure if all else is equal. But the intake valve is heavier so maybe you should shim the valve springs on the intake to get the open pressure higher or at least equal? Obviously you would have more seat pressure, too.
What about the opposite situation, with less exhaust lift? If the intake has enough pressure and the exhaust has less, do you just leave it be since it is lighter?
Or would you want a light side and heavy side, if both are adequate for their tasks? That way you could swap valve springs from intake to exhaust every once in a while to possibly increase their life.
This is all assuming the distance from coil bind is in the acceptable window for both intake and exhaust. Or is it important to optimize that distance for both?
I know so many questions. The main one is, would you shim the side with lower lift to get the same open pressure, especially if the lower lift one is the intake?
My current solid flat tappet cam has the same lift on both intake and exhaust even though it is a dual pattern so I kept the heights all the same. I am currently looking at solid roller profiles, some with the same lifts for intake and exhaust and some not.
thanks for any thoughts,
pl
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Depends on the degree of difference. If it's .020-.030", even on a 500 lb/in spring, that's only 10 lbs of spring pressure difference. Your valve springs will probably vary that much anyway. I'd rather have the install heights all dialed in right together and more importantly, on a solid roller, I'd rather have the coil bind clearances all right in there together.
BTW, even though the intake valve is larger/heavier, I put more emphasis on the exhaust valve, not because of the valve lift, but because the exhaust valve will be the one that tags a piston if it floats. I also put more emphasis on seat pressure rather than open pressure as that's what keeps the valves shut when they're supposed to be shut. The open pressure is a function of how aggressive the lobe is.
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Thanks! I wonder how often completely different springs are run on the intake and exhaust. Say if different lobe families are used. Not applicable to me, I'm not doing anything that intense. just wondering.
pl
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Thanks! I wonder how often completely different springs are run on the intake and exhaust. Say if different lobe families are used. Not applicable to me, I'm not doing anything that intense. just wondering.
pl
Not uncommon. And it's usually not because the lift is that much different, it's because the install heights are that different between intake/exhaust, or the rocker arm ratios are different.
If I vary the intake/exhaust lifts, it's usually not by much at all. I know lots of guys like doing the cams with more exhaust duration but less exhaust lift, or similar, but I personally have never seen that big of a correlation there.
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... I'd rather have the coil bind clearances all right in there together. ...
This! You want the coil bind clearance to be relatively small (like .050") and consistent in order to prevent coil surge / loss of valve control. I've found in my testing that damping the springs in this way is better than adding spring pressure.
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This! You want the coil bind clearance to be relatively small (like .050") and consistent in order to prevent coil surge / loss of valve control. I've found in my testing that damping the springs in this way is better than adding spring pressure.
Tight coil bind clearance to control surge is important for solid roller high rpm applications.
For street 5500 rpm cases with mild camshaft events tight coil bind clearance is certainly not a requirement.
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Thanks! I wonder how often completely different springs are run on the intake and exhaust. Say if different lobe families are used. Not applicable to me, I'm not doing anything that intense. just wondering.
pl
I've never used that, never had to. I would rely on my cam engineer to say what spring to use and supply them anyway. I have a setup for checking the springs, but I only set up my heads to hit the recommended installed height. Springs these days are pretty accurate in my experience. I have a set of mild solid flat Crane springs somewhere that were on a 238/248 Crane cam with about 600 passes on them and all 16 tested spec on when stored.
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The way that I do it, you have to know the open spring pressure that you need first, second, you have to know your max installed spring ht available. Your limited there, to your basic valve stem length but, you can get + .050 keepers, to increase it.
With the known, net lift, subtracted from the installed ht, you look through your spring catalog, for a spring that has a spring rate, in your min pressure range and is at least .050 to no more than .100 off coil bind. .060 has always been the number that I shoot for.
The coil bind clearance, has always been the most import spec to me. It gives the most longevity, because that the area that they should be made, to work in, for best harmonics and least spring surge.
Not worry about seat pressure, just shim for coil bind clearance and make sure you have enough open pressure for your application.
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Not worry about seat pressure, just shim for coil bind clearance and make sure you have enough open pressure for your application.
Frank, please clarify on what you mean here. Because surely you can't think that seat pressure isn't critical....
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Brent, you can't have both low seat pressure and high open pressure. Different engineered springs, will have a little difference in closed spring pressure but, you can not have what ever you want for closed pressure and optimum open pressure for open spec cam.
My criteria, is coil bind clearance as the most important aspect.
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Brent, you can't have both low seat pressure and high open pressure. Different engineered springs, will have a little difference in closed spring pressure but, you can not have what ever you want for closed pressure and optimum open pressure for open spec cam.
My criteria, is coil bind clearance as the most important aspect.
Yes, you can have low seat pressure and high open pressure. There are conical springs that give about 150 lbs seat and 630 open.
Yes, you can absolutely have whatever you want for closed pressure and optimum open pressure. Very easy, actually. With as many valve springs that are offered by Comp, Manley, PAC, PSI, Isky, etc., and with just as many ways of manipulating that, you can have whatever you want.
I'll add that seat pressure is as critical, if not more so, than open pressure. Seat is what makes the valve return to where it's supposed to be. I always look at seat pressure vs. install height first thing. Open isn't as critical to me at all, and to be honest, I use a very rudimentary way of choosing what open pressure I need. The seat pressure is chosen more carefully, based on the valve sizes, weights, cam lobe shape, rpm, etc. If you've ever seen someone break an exhaust valve head off, you'll not question whether or not they had enough open pressure.
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I spend quite a bit of time picking springs and agree with Brent, if you don’t manage closed pressure, you run the risk of bounce. Especially with a a heavy BBF or BBC valve
Although I do also look at open pressure, especially if I think the cam may be hard to control over the nose, what I don’t understand is the statement about not picking exactly all the parameters you want, in fact, I include coil bind in that too. The world is your oyster, there are so many options out there, I haven’t found a situation where I couldn’t control all numbers with parts choices and installed height adjustments
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So then, Brent, you do not care what the coil bind clearance is, right?
You'll run a spring .25 off coil blind or .000 clearance, right? What ever it takes to have low seat pressure, right?
Conical springs produce lower valve mass and can help but, they can't negate the need for open pressure.
So, give me a example of a actual spring, for a 8K (500 over rev factor) engine, with 1.78 installed ht, and .600 net lift and we will say 150 lb seat pressure. You say you an have anything you want, right? Oh, I forgot, it needs hyd rollers so I don't have to fiddle with it. What's the spring number I want?
I'll give you a break and won't require positive rotating retainers :)
We have ran 8k engines, for many years w/o conical springs. I would say, before you were born, even. As heavy a seat pressure as you had to take, to get the open pressure and longevity needed. Coil bind has to be addressed as well as fatigue.
For a street engine at 5500 or less, seat pressure isn't as important. Low lift and low duration, with longer ramps, won't get you into any area, where your gonna pull a valve apart or shorten valve seat life, beyond normal rebuild life. You can triple spring prices with conicals. That's fine, if you don't need the money someplace else. Each part in a engine costs money, there are a LOT of parts. I make my decisions of where I spend my money and I spend it wisely.
Correct coil bind settings, will lengthen spring life as that is where they are designed to work.
To answer the PO's question:
The main one is, would you shim the side with lower lift to get the same open pressure, especially if the lower lift one is the intake?
You want to set them at the same coil bind clearance, for best results.
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So then, Brent, you do not care what the coil bind clearance is, right?
You'll run a spring .25 off coil blind or .000 clearance, right? What ever it takes to have low seat pressure, right?
Conical springs produce lower valve mass and can help but, they can't negate the need for open pressure.
So, give me a example of a actual spring, for a 8K (500 over rev factor) engine, with 1.78 installed ht, and .600 net lift and we will say 150 lb seat pressure. You say you an have anything you want, right? Oh, I forgot, it needs hyd rollers so I don't have to fiddle with it. What's the spring number I want?
I'll give you a break and won't require positive rotating retainers :)
We have ran 8k engines, for many years w/o conical springs. I would say, before you were born, even. As heavy a seat pressure as you had to take, to get the open pressure and longevity needed. Coil bind has to be addressed as well as fatigue.
For a street engine at 5500 or less, seat pressure isn't as important. Low lift and low duration, with longer ramps, won't get you into any area, where your gonna pull a valve apart or shorten valve seat life, beyond normal rebuild life. You can triple spring prices with conicals. That's fine, if you don't need the money someplace else. Each part in a engine costs money, there are a LOT of parts. I make my decisions of where I spend my money and I spend it wisely.
Correct coil bind settings, will lengthen spring life as that is where they are designed to work.
To answer the PO's question:
The main one is, would you shim the side with lower lift to get the same open pressure, especially if the lower lift one is the intake?
You want to set them at the same coil bind clearance, for best results.
I'm typing this slow because I know you can't read fast.
Look up above. Look at what I said about coil bind clearance. Look at what WConley quoted me saying about coil bind clearance.
Does it look like I don't care about coil bind clearance? I routinely run .050-.060" and believe it or not, some spring manufacturers specifically want some of their springs at .100" CBC, so I do that sometimes too.
NOT ONE engine builder looks at the open pressure only without looking at the seat pressures to make sure the valves don't float to eternity and if you think that seat pressure in a street engine at 5500 or less isn't important, you've got more to learn than what I thought. Go build an FE with a hydraulic roller at 5500 and tell me seat pressure isn't important when you're listening to the valves float.
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Seems to be some consensus that the distance to coil bind height might be the number one priority, at least on a solid roller.
Also seems to be some consensus that the other factors are important, too. Can't optimize one measure without any consideration to the others.
pl
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Seems to be some consensus that the distance to coil bind height might be the number one priority, at least on a solid roller.
Also seems to be some consensus that the other factors are important, too. Can't optimize one measure without any consideration to the others.
pl
Not my position, in fact just look at Manley vs PAC both have entirely different bind distance recommendations. No benefit or wisdom by putting one variable ahead of another.
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I agree with seat pressure and coil bind being the most important. On a big Cam high winder the seat pressure and lash get's checked after every pass. If a spring is going away it comes out. Open pressure is whatever the spring spec makes it.
Got lift?
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Seems to be some consensus that the distance to coil bind height might be the number one priority, at least on a solid roller.
Also seems to be some consensus that the other factors are important, too. Can't optimize one measure without any consideration to the others.
pl
Not my position, in fact just look at Manley vs PAC both have entirely different bind distance recommendations. No benefit or wisdom by putting one variable ahead of another.
Right. In some discussions with my PAC rep, there were a few springs that they recommended running at .100" coil bind clearance. Some others were .050". Manley gives you a warning, something like, "DO NOT GO UNDER THIS RECOMMENDED OPEN HEIGHT OR SPRING DAMAGE CAN OCCUR" . I ignored them once on a bracket engine and set them up at .060" coil bind clearance. It broke a valve spring during a season.
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Oh my gosh. The sky is blue.
pl
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This! You want the coil bind clearance to be relatively small (like .050") and consistent in order to prevent coil surge / loss of valve control. I've found in my testing that damping the springs in this way is better than adding spring pressure.
I remember when you ran this test. Pretty enlightening. Might be worth a re-post as a refresher
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Barry -
I'm going to have to dig through some of my old hard drives in the drawer. That was a while ago... The post write-ups haven't made it to my current archives.
Where did all of the time go? The good news is that the spin test machine is about to ride again, but doing something completely different!
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Classic cinema:
https://youtu.be/AdeSc-8gNQw
https://youtu.be/yVwzXeAtEHg
https://youtu.be/MXrQw8cXEiI
https://youtu.be/BBxVPOCrznQ
https://youtu.be/kFbfHF9gzTY
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Nightmist - That last video really underscores the benefits of running near coil bind. That's 10,000 rpm!
Of course, the spring has to be able to take that kind of deflection as Brent alluded to.
Thanks!
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So then, Brent, you do not care what the coil bind clearance is, right?
You'll run a spring .25 off coil blind or .000 clearance, right? What ever it takes to have low seat pressure, right?
Conical springs produce lower valve mass and can help but, they can't negate the need for open pressure.
So, give me a example of a actual spring, for a 8K (500 over rev factor) engine, with 1.78 installed ht, and .600 net lift and we will say 150 lb seat pressure. You say you an have anything you want, right? Oh, I forgot, it needs hyd rollers so I don't have to fiddle with it. What's the spring number I want?
I'll give you a break and won't require positive rotating retainers :)
We have ran 8k engines, for many years w/o conical springs. I would say, before you were born, even. As heavy a seat pressure as you had to take, to get the open pressure and longevity needed. Coil bind has to be addressed as well as fatigue.
For a street engine at 5500 or less, seat pressure isn't as important. Low lift and low duration, with longer ramps, won't get you into any area, where your gonna pull a valve apart or shorten valve seat life, beyond normal rebuild life. You can triple spring prices with conicals. That's fine, if you don't need the money someplace else. Each part in a engine costs money, there are a LOT of parts. I make my decisions of where I spend my money and I spend it wisely.
Correct coil bind settings, will lengthen spring life as that is where they are designed to work.
To answer the PO's question:
The main one is, would you shim the side with lower lift to get the same open pressure, especially if the lower lift one is the intake?
You want to set them at the same coil bind clearance, for best results.
I'm typing this slow because I know you can't read fast.
Brent, I note that you've heavily edited this post. I read most of it when out for dinner, with my wife, while waiting for dinner. To address one of the edited portions of your post, I was building a roller cam, 427, when you were in diapers. I also read with comprehension and know how to multiply.
Look up above. Look at what I said about coil bind clearance. Look at what WConley quoted me saying about coil bind clearance.
Does it look like I don't care about coil bind clearance? I routinely run .050-.060" and believe it or not, some spring manufacturers specifically want some of their springs at .100" CBC, so I do that sometimes too.
I'm glad you, at least are taking my advice about setting coil bind at .050 - .100, thank you.
NOT ONE engine builder looks at the open pressure only without looking at the seat pressures to make sure the valves don't float to eternity and if you think that seat pressure in a street engine at 5500 or less isn't important, you've got more to learn than what I thought. Go build an FE with a hydraulic roller at 5500 and tell me seat pressure isn't important when you're listening to the valves float.
I never said you ignore seat pressure, what I was referring to, is AFTER you pick a spring with enough open pressure and CB clearance, to keep the lifter in contact with the lobe, you don't have any choice on the seat pressure. Move one, you move the other, with the same lift or, do you have a way to change that, conical or not? I grant you conical springs, reduce valve weight and adding a LW retainer, allowing less open pressure and that helps but, there is a limit and I want to be sure the lifter stays on the lobe. Also, not everyone wants or can afford conical's. Good springs are not cheap and double that for conical springs.
You have, one lift, to control, per lobe, you need to set the CB clearance with that lift and that only leaves you with one seat pressure. W/o the correct open pressure, you stand the real and detrimental case of the lifter lofting over the lobe and crashing on the closing ramp and seat.
If your seat pressure is greater than you want and you think it may bounce on the seat, you change the rate of the closing side of the ramp, to slow it down.
I think you need to talk to a cam grinder and discuss closing ramp rates, it may solve some of your cam problems.
If a spring mfg says not to do something, I lesson and would ask why. Broken springs are bad. You also need to know what they are used for. Case in point, the Open Comp car (oval track not drag racing), I sponsored lessened to a drag engine builder and he talked them into his springs, it cost them a whole engine. Do your research, and ask questions, not all springs are created equal.
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Frank, you are into oval track ?? ..... 4 cylinder, 8 cylinder ??
Was curious as to lofting lifters, read some articles where some lofted lifters to open the valve higher
What kind of closing ramp would they have had to make the parts survive ??
Ricky.
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Frank, you are into oval track ?? ..... 4 cylinder, 8 cylinder ??
Was curious as to lofting lifters, read some articles where some lofted lifters to open the valve higher
What kind of closing ramp would they have had to make the parts survive ??
Ricky.
Ricky, those are called cheater cams. They're extremely hard on everything, but in a rules application where you have a lift rule, it's a good way to get around it. The lift will check correct at tech but it will throw more lift in there when the engine is running.
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So then, Brent, you do not care what the coil bind clearance is, right?
You'll run a spring .25 off coil blind or .000 clearance, right? What ever it takes to have low seat pressure, right?
Conical springs produce lower valve mass and can help but, they can't negate the need for open pressure.
So, give me a example of a actual spring, for a 8K (500 over rev factor) engine, with 1.78 installed ht, and .600 net lift and we will say 150 lb seat pressure. You say you an have anything you want, right? Oh, I forgot, it needs hyd rollers so I don't have to fiddle with it. What's the spring number I want?
I'll give you a break and won't require positive rotating retainers :)
We have ran 8k engines, for many years w/o conical springs. I would say, before you were born, even. As heavy a seat pressure as you had to take, to get the open pressure and longevity needed. Coil bind has to be addressed as well as fatigue.
For a street engine at 5500 or less, seat pressure isn't as important. Low lift and low duration, with longer ramps, won't get you into any area, where your gonna pull a valve apart or shorten valve seat life, beyond normal rebuild life. You can triple spring prices with conicals. That's fine, if you don't need the money someplace else. Each part in a engine costs money, there are a LOT of parts. I make my decisions of where I spend my money and I spend it wisely.
Correct coil bind settings, will lengthen spring life as that is where they are designed to work.
To answer the PO's question:
The main one is, would you shim the side with lower lift to get the same open pressure, especially if the lower lift one is the intake?
You want to set them at the same coil bind clearance, for best results.
I'm typing this slow because I know you can't read fast.
Brent, I note that you've heavily edited this post. I read most of it when out for dinner, with my wife, while waiting for dinner. To address one of the edited portions of your post, I was building a roller cam, 427, when you were in diapers. I also read with comprehension and know how to multiply.
Look up above. Look at what I said about coil bind clearance. Look at what WConley quoted me saying about coil bind clearance.
Does it look like I don't care about coil bind clearance? I routinely run .050-.060" and believe it or not, some spring manufacturers specifically want some of their springs at .100" CBC, so I do that sometimes too.
I'm glad you, at least are taking my advice about setting coil bind at .050 - .100, thank you.
NOT ONE engine builder looks at the open pressure only without looking at the seat pressures to make sure the valves don't float to eternity and if you think that seat pressure in a street engine at 5500 or less isn't important, you've got more to learn than what I thought. Go build an FE with a hydraulic roller at 5500 and tell me seat pressure isn't important when you're listening to the valves float.
I never said you ignore seat pressure, what I was referring to, is AFTER you pick a spring with enough open pressure and CB clearance, to keep the lifter in contact with the lobe, you don't have any choice on the seat pressure. Move one, you move the other, with the same lift or, do you have a way to change that, conical or not? I grant you conical springs, reduce valve weight and adding a LW retainer, allowing less open pressure and that helps but, there is a limit and I want to be sure the lifter stays on the lobe. Also, not everyone wants or can afford conical's. Good springs are not cheap and double that for conical springs.
You have, one lift, to control, per lobe, you need to set the CB clearance with that lift and that only leaves you with one seat pressure. W/o the correct open pressure, you stand the real and detrimental case of the lifter lofting over the lobe and crashing on the closing ramp and seat.
If your seat pressure is greater than you want and you think it may bounce on the seat, you change the rate of the closing side of the ramp, to slow it down.
I think you need to talk to a cam grinder and discuss closing ramp rates, it may solve some of your cam problems.
If a spring mfg says not to do something, I lesson and would ask why. Broken springs are bad. You also need to know what they are used for. Case in point, the Open Comp car (oval track not drag racing), I sponsored lessened to a drag engine builder and he talked them into his springs, it cost them a whole engine. Do your research, and ask questions, not all springs are created equal.
Frank, I just figured out what you're doing and it's very cunning. If you hang around long enough and start enough arguments with engine builders, you'll figure out which parts to use on your SBF build. That's a good way to look knowledgeable and save face! Kudos to you! So far, we've helped you with pushrod diameter, valve spring pressure requirements, and that Erector Set main girdle that you built. You're well on your way now!
Frank: "You need to save weight on pushrods."
Engine builders: "No, you need to use the largest diameter, most rigid, pushrod that you can fit."
Argument ensues. *Frank furiously taking notes, "Small pushrod bad. Big pushrod good."*
Frank: "Seat pressure isn't critical."
Engine builders: "Seat pressure is arguably more critical than open."
Argument ensues. *Frank writing: "Ok, seat pressure IS important."
I get it now! You're such a sly one, Frank.
Since you apparently only have access to a 1969 TRW parts book, just let me know if you need any help picking valve springs and components for your build. I have access to a lot of stuff and a lot of technology has changed since you built that 427 50 years ago.
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Seems to be some consensus that the distance to coil bind height might be the number one priority, at least on a solid roller.
Also seems to be some consensus that the other factors are important, too. Can't optimize one measure without any consideration to the others.
pl
Not my position, in fact just look at Manley vs PAC both have entirely different bind distance recommendations. No benefit or wisdom by putting one variable ahead of another.
"Can't optimize one measure without any consideration to the others."
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Paulie,
Here's some data for you.
This is a 556ci BBF pulling engine. Makes over 1200 hp at 8500-9000 peak. Valve springs are PAC, 1.525" OD, seat pressures and coil bind dimensions were individually measured per valve spring, as they can vary.
(https://live.staticflickr.com/65535/46760220645_ebfe08e030_z.jpg)
If you can look through my chicken scratch, you will see that they're all at 400 lbs seat. Most spring pressure testers won't measure accurately past 1000 lbs (my Intercomp won't), so I carefully measure seat pressure and calculate the open pressure based on seat pressure, valve lift, and the spring constant. You'll also see that the spring coil bind dimensions vary by quite a bit, so upon assembly, they are mixed and matched per the install height dimension.
(https://live.staticflickr.com/65535/33798686028_40c55cbc90_z.jpg)
Geometry is set to minimize valve lift loss. This is a .050" pattern with almost an inch of lift.
(https://live.staticflickr.com/65535/33798679858_2c0b160d91_z.jpg)
As you can see, there's about .020-.025" difference between intake/exhaust install heights and I used the same spring on both. The intake valve gets a little taller install height. This is with a 2.450" intake valve, albeit an 11/32" Victory titanium valve.
This engine uses one of my custom solid rollers, with .975"/.950" gross lift. Coil bind clearance varies from .050"-.090" depending on whether it's an intake valve or exhaust valve. I was given a blessing by my PAC rep. (And before Frank says I "stole" his advice, these pictures are 2 years old.)
It runs from 8500-9000 rpm and has been freshened up twice. Upon freshen ups, I always recheck the valve spring pressures and I've only seen 18 lbs loss of seat pressure at the most so far.
Spring technology has really advanced in the past 10 years. It used to be that guys would run 1.625-1.650" diameter triple springs in these applications. These are pretty small dual springs but are well up to the challenge. Not cheap though.
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Thanks everybody! Lots of good information. Seems to be several schools of thought to get to basically the same place, which I think is valve control without superfluous spring pressure.
It'll definitely help me set up my springs. I don't always buy everything from the same manufacturer. No magic in that, in my opinion. I have a Comp cam, Crane springs and retainers, Crower lifters, and Manton pushrods on my current setup, for instance.
I have had problems with spring harmonics in the past. Aggressive cam lobes with not enough spring pressure and too light and wiggly pushrods. I ended breaking valve springs. I found a good tech at Crane and he helped me figure it out. I actually ended up with a combination with a lot of distance from coil bind (.205" I think?), but it is working for me. This is a flat tappet, though.
So lots of variables to consider and impossible to put into a short response and still cover everything.
Keep it coming! I'd love to see your post, Bill.
pl
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Paulie,
Here's some data for you.
Thanks Brent! I will digest that info. I gotta go play with chemicals for a while.....
pl
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Wow Brent, now your a mind reader. You need to put that on your business card, too.
Frank, I just figured out what you're doing and it's very cunning. If you hang around long enough and start enough arguments with engine builders, you'll figure out which parts to use on your SBF build. That's a good way to look knowledgeable and save face! Kudos to you! So far, we've helped you with pushrod diameter, valve spring pressure requirements, and that Erector Set main girdle that you built. You're well on your way now!
Frank: "You need to save weight on pushrods."
Engine builders: "No, you need to use the largest diameter, most rigid, pushrod that you can fit."
Argument ensues. *Frank furiously taking notes, "Small pushrod bad. Big pushrod good."*
Rather than make up what I say, I'd rather that you find the post and do direct quotes. Is that asking to much?
Regarding the push rod topic, what I actually said, had nothing to do with the size of the push rod. I asked, why run the oil threw the push rod, like you do with your rockers, since it adds weight, rather than use the std oil system, with dry push rods. I don't know why that upsets you?
Frank: "Seat pressure isn't critical."
Engine builders: "Seat pressure is arguably more critical than open."
Argument ensues. *Frank writing: "Ok, seat pressure IS important."
Again, what I actually said, was that I want the lifter and lobe, to remain in contact, with ~.060 CBC, FIRST, take what you get with seat pressure and if that has to be addressed, use the heal, to address it.
I get it now! You're such a sly one, Frank.
Again your mind reading skills kick in :))
Since you apparently only have access to a 1969 TRW parts book, just let me know if you need any help picking valve springs and components for your build. I have access to a lot of stuff and a lot of technology has changed since you built that 427 50 years ago.
At 7K the valve train, had no issues, with the SL, Chet Herbert Roller cam. He directed me to the right springs, rather than suggesting .600 springs, for a .670 cam as I saw done last May. Math skills again?
« Last Edit: Today at 03:57:50 AM by blykins »
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Brent Lykins
Lykins Motorsports
Custom FE Street, Drag Race, Road Race, and Pulling Truck Engines
Custom Roller & Flat Tappet Camshafts
www.lykinsmotorsports.com
brent@lykinsmotorsports.com
www.customfordcams.com
502-759-1431
Instagram: brentlykinsmotorsports
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Last post, between Brent and I on this subject, I'll move on.
If Brent wants to ignore, lift loft, so be it. I think most of us know how to set CBC by now and I'll address seat bounce, with my own relational.
Other can use this info, in their own way.
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Wow Brent, now your a mind reader. You need to put that on your business card, too.
Frank, I just figured out what you're doing and it's very cunning. If you hang around long enough and start enough arguments with engine builders, you'll figure out which parts to use on your SBF build. That's a good way to look knowledgeable and save face! Kudos to you! So far, we've helped you with pushrod diameter, valve spring pressure requirements, and that Erector Set main girdle that you built. You're well on your way now!
Frank: "You need to save weight on pushrods."
Engine builders: "No, you need to use the largest diameter, most rigid, pushrod that you can fit."
Argument ensues. *Frank furiously taking notes, "Small pushrod bad. Big pushrod good."*
Rather than make up what I say, I'd rather that you find the post and do direct quotes. Is that asking to much?
Regarding the push rod topic, what I actually said, had nothing to do with the size of the push rod. I asked, why run the oil threw the push rod, like you do with your rockers, since it adds weight, rather than use the std oil system, with dry push rods. I don't know why that upsets you?
Frank: "Seat pressure isn't critical."
Engine builders: "Seat pressure is arguably more critical than open."
Argument ensues. *Frank writing: "Ok, seat pressure IS important."
Again, what I actually said, was that I want the lifter and lobe, to remain in contact, with ~.060 CBC, FIRST, take what you get with seat pressure and if that has to be addressed, use the heal, to address it.
I get it now! You're such a sly one, Frank.
Again your mind reading skills kick in :))
Since you apparently only have access to a 1969 TRW parts book, just let me know if you need any help picking valve springs and components for your build. I have access to a lot of stuff and a lot of technology has changed since you built that 427 50 years ago.
At 7K the valve train, had no issues, with the SL, Chet Herbert Roller cam. He directed me to the right springs, rather than suggesting .600 springs, for a .670 cam as I saw done last May. Math skills again?
« Last Edit: Today at 03:57:50 AM by blykins »
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Brent Lykins
Lykins Motorsports
Custom FE Street, Drag Race, Road Race, and Pulling Truck Engines
Custom Roller & Flat Tappet Camshafts
www.lykinsmotorsports.com
brent@lykinsmotorsports.com
www.customfordcams.com
502-759-1431
Instagram: brentlykinsmotorsports
Wow, you win, Frank. You called me out on a post where I got part numbers mixed up, was corrected on it, and then I apologized. I guess that was a crime against humanity that just can't be forgiven. BTW, that has nothing to do with the discussion we're having on valve springs, coil bind clearance, or remotely anything of the like, but I guess you gotta get your jabs where you can, right?
And just so you know I'm not making anything up, here's a direct quote, straight from your keyboard, in response to a post that I made on April 6th of this year stating that pushrod weight has no bearing on the springs/valves/etc...:
"If this is true, then the weight of the lifter, means nothing also and why do you use aluminum rockers?
I was taught that the weight of everything in the valve train means something and that lighter, w/o failure, increases rpm, given the same spring pressure. Am I wrong there, too?"
On April 11th, following that post, since you didn't believe us here on the weight of pushrods/lifters affecting rpm levels, you posted on Speed Talk and asked this question: "How much does the weight on the lifter/push side of the valve train effect increasing the rpm potential?" You were schooled there as well.
My point is, Frank, you would be much better off, when faced with something that goes against your "understanding", if you would just approach it with a larger degree of tact and open-mindedness, considering a lot of what you know is extremely outdated.
By the way, I know you're wanting to get one last jab in, but I don't ignore lift loft either. I choose springs correctly, based on seat pressure, open pressure, lift, and whatever other voodoo you want to consider mixed in there. Have you ever had to design a camshaft that lofts the valves on purpose? I have.
Good luck, Franky boy.
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Last post, between Brent and I on this subject, I'll move on.
If Brent wants to ignore, lift loft, so be it. I think most of us know how to set CBC by now and I'll address seat bounce, with my own relational.
Other can use this info, in their own way.
This entire thread turned ridiculous. It's like which a plant needs more, food, water or sunlight? Take one away, it dies regardless.
I know Brent well, in-person friendship, he and I talk and have very different techniques at times, but he doesn't ignore loft, nor does he ignore coil bind, nor do I or anyone else worth their salt. They all matter. However, he, like I, generally control loft by having a lobe that is controllable not by jamming open pressure, if you are there, unless you have a very serious reason, you are wasting power and reliability to spring pressure. Many are not controllable and require much more spring pressure than a equally powerful and controllable cam would.
The thing I see though, and agree with Brent fully, is that often a manufacturer's recommendation has them a little light on the seat, so it's best to fix it. However, you need the right spring and setup, period.
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This entire thread turned ridiculous.
It certainly has. Guys, there is room for more than one opinion here. PLEASE tone it down.
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Paulie,
Here's some data for you.
Thanks Brent! I will digest that info. I gotta go play with chemicals for a while.....
pl
Well that is some serious stuff for sure. I looked back at my notes and my intake heights (Ebok FE heads) varied from 1.942" to 1.957". My exhaust heights varied from 1.922" to 1.935". I shimmed all my intakes by varying amounts and shimmed one of my exhausts to get my final values all in the 1.922"-1.930" range.
I am not sure how good my measurement technique is, though. I assume you have to use some "authority" to get the valve seated well enough to give you a good value without a spring on there?
I also didn't measure my pressures, but theoretically they are pretty close.
pl
[/quote]
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Man...I enjoyed this thread. The rather violent valve float videos were very educational. Seeing all the shimmy or wobble of those springs makes me think the conical type have a great advantage in that the always changing dimensions reduce harmonics. Not that I care about Uber high RPM operation but the occasional over rev' is bound to happen.
Also learned that trolling engine builders might not be ideal.
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Man...I enjoyed this thread. The rather violent valve float videos were very educational. Seeing all the shimmy or wobble of those springs makes me think the conical type have a great advantage in that the always changing dimensions reduce harmonics. Not that I care about Uber high RPM operation but the occasional over rev' is bound to happen.
Also learned that trolling engine builders might not be ideal.
There was no trolling that I saw in the initial responses, at all. Just different opinions. Did I mention that the sky is blue? :)
pl
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Man...I enjoyed this thread. The rather violent valve float videos were very educational. Seeing all the shimmy or wobble of those springs makes me think the conical type have a great advantage in that the always changing dimensions reduce harmonics. Not that I care about Uber high RPM operation but the occasional over rev' is bound to happen.
Also learned that trolling engine builders might not be ideal.
There was no trolling that I saw in the initial responses, at all. Just different opinions. Did I mention that the sky is blue? :)
pl
But is your blue sky the same as my blue sky?
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Some camshafts are ground with lobe intensity that cannot be controlled by any normal or close to normal valve spring pressures. I had a custom camshaft ground for my EMC entry in 2019 with .370" lobe lift and 1.6 roller rocker arms. I had valve float at 6600 rpm and could not contain the valve float by changing 3 sets of heads, 5 sets of valve springs, but did finally get the engine to rev to 7100 before valve float and nose dive on dyno. After the EMC, I changed the camshaft to an Isky that we had ordered before the EMC but came too late to test. I simply removed the custom camshaft, left the Trend tool steel lifters in place, and installed the new Isky camshaft. .370" lobes, and almost identical camshaft specs. On the warm up pulls and after the camshaft was deemed ready, the lash checked for wear, we made a pull and the engine pulled to 7300 rpm without a hick-up and made 12 more horsepower. We made several pulls to 7300 rpm and changed several intake manifolds, and the engine never missed a beat. The special custom camshaft simply could not be controlled with any of the 5 different sets of valve springs. Ran great up to 6500 rpm, but that was all it would smoothly handle. We set the seat pressures all the way up to 165#, and coil bind at .040" and still could not control valve float. The over the nose pressure exceeded the camshaft manufacturer's warranty for going flat, so we did everything by the book. The valves were 5/16" stems, titanium retainers, 5/16 chromoly push rods, HS roller rocker arms, everything first class. The springs used on both camshafts at the end were the same set. Joe-JDC
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Hey Joe, I’m thinking out loud to myself. Did those 2 camshafts have identical base circles?
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The custom camshaft was designed to run .009" hot lash, and the Isky .016" hot lash. I have not measured the base circle diameter, but we moved the rocker arm stands with shims, and changed three different length pushrods to get the geometry perfect with both camshafts. Joe-JDC
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Really good thread, admittedly never messed with anything FE that was going to turn enough RPM to worry much about valve float, but now I’m pondering a build that will and this info is very helpful. I never quite understood the “use the biggest pushrod” angle until I watched the valve float videos a few years ago and it clicked that it’s harmonics not just “loft” that causes float.
I did buy an Intercomp tester on EBay because through years of horse trading I have a bunch of valve springs with no clue on specs. I also have had the opportunity to check springs on four sets of assembled heads and I’ll tell you it’s scary what I found for seat pressures on a few. These were fresh rebuilt heads of unknown provenance, but there’s no wonder some guys have issues with float even with a 5500rpm cam, and I suspect it’s why the Edelbrocks I had seemed to struggle over 5000. I will say the BBMs I bought secondhand but setup by Brent were spot on, and consequently can do 6000 no problem, even though the rest of the hydro roller valvetrain is sort of a hodgepodge of parts, but some guys have reported hydro rollers struggling over 5500 (with 6300ish being a more common upper limit)
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....but some guys have reported hydro rollers struggling over 5500 (with 6300ish being a more common upper limit)
That used to be the case about 12-13 years ago. If you checked the forums back then, everyone thought that 5500 rpm was like a wall that couldn't be penetrated. Now we're touching 7500.
https://www.youtube.com/watch?v=C_JY47anClA
A lot of guys don't understand how heavy some FE components are....especially if you're still running 3/8" stem valves. Even the 11/32" valves are heavy compared to BBC standards. Coupling heavy valves with inadequate seat pressures and aggressive lobes exacerbated the issue. I learned a big lesson when I tried Comp XFI lobes. Customer constantly complained of noise and not being able to pull the rpms. It didn't make sense to me that I could build a SBF that would turn 7000 with a hydraulic roller, but had trouble with FE's, so that led to a lot of dyno testing and experimentation.
On a separate note....
Joe, I used a camshaft ground by that gentleman before in a 445ci Windsor. It was a hydraulic roller and was so aggressive that it was showing all kinds of valvetrain issues (float, laziness up top, etc.), even with his recommended valve spring pressures. That's why I started doing my own thing.
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Well that is some serious stuff for sure. I looked back at my notes and my intake heights (Ebok FE heads) varied from 1.947" to 1.957". My exhaust heights varied from 1.922" to 1.935". I shimmed all my intakes by varying amounts and shimmed one of my exhausts to get my final values all in the 1.922"-1.930" range.
I am not sure how good my measurement technique is, though. I assume you have to use some "authority" to get the valve seated well enough to give you a good value without a spring on there?
I also didn't measure my pressures, but theoretically they are pretty close.
Paulie,
You did well, and that's likely why it works well, combined with a cam lobe that supports it. The next step would have been to check the springs to see if the installed height was what the actual springs wanted, check open pressure, and continue through to coil bind.
Wild thing is, its about 800-1000 for a ticket to an accurate spring pressure tester, cheap ones are all over the map. I used Brent's Intercomp and then went and bought one for myself.
As far as measuring installed height, using a spring micrometer is pretty easy, make sure it fits the retainer properly, and zonk it down. Using a fine thread and a knurled surface, it's not hard to exceed closed pressure. Not exact, without heat in the seat and valve but you are also likely exceeding pressure and compensating automatically...(I don't purposely compensate, I just like to try to forecast where my measurements may change, and the advantage of the threads gives plenty of leverage)
In fact, it makes me want to go see how much pressure I can put in the spring tester by expanding the spring mic :) After our "spring" cleaning is done...mama says we need to make the house right LOL
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....but some guys have reported hydro rollers struggling over 5500 (with 6300ish being a more common upper limit)
That used to be the case about 12-13 years ago. If you checked the forums back then, everyone thought that 5500 rpm was like a wall that couldn't be penetrated. Now we're touching 7500.
https://www.youtube.com/watch?v=C_JY47anClA
A lot of guys don't understand how heavy some FE components are....especially if you're still running 3/8" stem valves. Even the 11/32" valves are heavy compared to BBC standards. Coupling heavy valves with inadequate seat pressures and aggressive lobes exacerbated the issue. I learned a big lesson when I tried Comp XFI lobes. Customer constantly complained of noise and not being able to pull the rpms. It didn't make sense to me that I could build a SBF that would turn 7000 with a hydraulic roller, but had trouble with FE's, so that led to a lot of dyno testing and experimentation.
On a separate note....
Joe, I used a camshaft ground by that gentleman before in a 445ci Windsor. It was a hydraulic roller and was so aggressive that it was showing all kinds of valvetrain issues (float, laziness up top, etc.), even with his recommended valve spring pressures. That's why I started doing my own thing.
Preaching to the choir here, but the other factor is oil. Who would have expected that we would be building performance FEs, for regular street use, with 10w30. When I was young, first thing oil change would get Kendall Green 20w50...race ready LOL If the standard old school warrior fills up his HR engine with his favorite 20w50 or 30w, it's a different story, even if they do play by the other rules.
But man, I do remember that Windsor cam, what a mess, and to the question on base circles, a monster with small base circles and steep ramps could get ugly. However, the uncontrollable lobes we are talking, are the differences from a Lunati Voodoo HR oor as Brent mentioned, an XFI lobe, compared to a Comp Magnum on a standard 1.438 base circle. There is a trade off, slower ramps (lazy) add advertised and overlap, but if that is managed (and manageable) for the build, the lazy lobe will "generally" be easier to control. That goes for flat tappets and solids too.
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Man...I enjoyed this thread. The rather violent valve float videos were very educational. Seeing all the shimmy or wobble of those springs makes me think the conical type have a great advantage in that the always changing dimensions reduce harmonics. Not that I care about Uber high RPM operation but the occasional over rev' is bound to happen.
Also learned that trolling engine builders might not be ideal.
There was no trolling that I saw in the initial responses, at all. Just different opinions. Did I mention that the sky is blue? :)
pl
But is your blue sky the same as my blue sky?
zactly! ;D ;)
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Well that is some serious stuff for sure. I looked back at my notes and my intake heights (Ebok FE heads) varied from 1.947" to 1.957". My exhaust heights varied from 1.922" to 1.935". I shimmed all my intakes by varying amounts and shimmed one of my exhausts to get my final values all in the 1.922"-1.930" range.
I am not sure how good my measurement technique is, though. I assume you have to use some "authority" to get the valve seated well enough to give you a good value without a spring on there?
I also didn't measure my pressures, but theoretically they are pretty close.
Paulie,
You did well, and that's likely why it works well, combined with a cam lobe that supports it. The next step would have been to check the springs to see if the installed height was what the actual springs wanted, check open pressure, and continue through to coil bind.
Wild thing is, its about 800-1000 for a ticket to an accurate spring pressure tester, cheap ones are all over the map. I used Brent's Intercomp and then went and bought one for myself.
As far as measuring installed height, using a spring micrometer is pretty easy, make sure it fits the retainer properly, and zonk it down. Using a fine thread and a knurled surface, it's not hard to exceed closed pressure. Not exact, without heat in the seat and valve but you are also likely exceeding pressure and compensating automatically...(I don't purposely compensate, I just like to try to forecast where my measurements may change, and the advantage of the threads gives plenty of leverage)
In fact, it makes me want to go see how much pressure I can put in the spring tester by expanding the spring mic :) After our "spring" cleaning is done...mama says we need to make the house right LOL
Thanks Ross. I've run mine up to 7300 with no issues, though I think I ought to shift around 6800-6900. Just a solid flat tappet, but aggressive lobes. I don't think I'll be buying a spring pressure tester as I wouldn't use it very often. Be nice to have one, though. That's an interesting thought regarding exceeding the true spring pressure with the micrometer. I haven't used mine in some time, but I seem to remember not feeling super confident about how hard to twist it. It seems like I could change the measured height depending on how frisky I was feeling.
pl
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I tighten mine right down, within reason, I am not using vise grips or anything LOL That being said, you may add a little with strong hands, but not so much to change spring pressure that much
That being said, what are you running for a cam, (.050 and advertised and brand) and which springs?
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Comp Cams 279/287 advertised, 252/260 @0.050". Crane 96879 springs.
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So a general question about measurements confidence. When you have doubts, how do you address them?
Personally I'm fond of taking multiple measurements (three typically) in order to see how repeatable my setup is. It's time consuming since you have to breakdown and reassemble/realign your tools and gauge. It's a hobby for me vs a business. With experience and knowledge of what to expect this becomes redundant I suppose.
Absolutely accuracy depends on calibrated tools and that's some next level stuff. I'm reminded of Jay's posts about calibrating his torque wrenches at home. It's the value you should get when paying someone for the work. Important but can be mitigated by taking the part supplier's measurements and backing them up with your own. Always a wise step. What came in the box might not be what was measured on the data sheet. It happens.
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So a general question about measurements confidence. When you have doubts, how do you address them?
Personally I'm fond of taking multiple measurements (three typically) in order to see how repeatable my setup is. It's time consuming since you have to breakdown and reassemble/realign your tools and gauge. It's a hobby for me vs a business. With experience and knowledge of what to expect this becomes redundant I suppose.
Absolutely accuracy depends on calibrated tools and that's some next level stuff. I'm reminded of Jay's posts about calibrating his torque wrenches at home. It's the value you should get when paying someone for the work. Important but can be mitigated by taking the part supplier's measurements and backing them up with your own. Always a wise step. What came in the box might not be what was measured on the data sheet. It happens.
I think confidence comes with usage.
Your point about calibration is paramount though. I never pick up a mic without checking it on a standard. You can check a spring mic against a set of calipers. You can calibrate torque wrenches. There are also checking springs for spring testers.
Once I know everything is calibrated, the measurements I get are what they are and then I look at how to deal with them.
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Same here, first time I used each of my spring mics, I checked with calipers, on the first one I checked with a 1-2 mic as well. Now what I do is after the first measurement I just check with calipers at the height I am playing. However, realize with springs, even at a 400 lb rate, .01 is only 4 lbs, it's not the same as measuring oil clearances.
With all other stuff, I do the same as Brent, stick a standard in it before I start and any time I don't like what I am seeing I do it again. With a bore gauge, I check zero in the mic before every hole, and same thing, if I don't like what I see, first step is check mic, check zero on gauge, and go from there.
Amazingly, room temp causes me more fits on a cold day than anything. Nebraska winters I have to let the shop warm up or bore gauges go wonky
This is one of those "takes longer to type than to do" posts, you get in a rhythm that includes check periodically and check when the loose nut running the tool gets an odd number.
As far as the spring tester. I have a set of springs Brent tested for me when we were comparing tools, they tested the same on mine when I bought it. I toss one of those on the tester if I don't see the numbers I expect, but name brand springs have been pretty consistent lately.
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Yup! Trust but verify. I always check my tool setter on the CNC with gauge blocks. You never know whose paws have been on your tools.
I remember years ago when I worked in my school's aeronautical engineering machine shop. The head of the shop had some nice vintage Starrett micrometers. Some dimwit PhD student decided they would be great drill press clamps :o
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I forgot to add...
On spring mics, I tighten them by hand until I can't make them move anymore. Just habit. A couple thou of install height distance isn't going to be of any kind of detriment though. Your valve spring won't know .002-.003" and if you're dialing in coil bind clearance, .048" is going to be the same as .050" or .052". As a matter of fact, I can guarantee you that when the engine is running, you're going to have more clearance than what you think you had.
If you set up all your springs thinking you have .600" at the valve, check it with your actual valve spring and pushrod. You'd be surprised sometimes at the amount of lift you lose and that goes up with spring pressure or inadequate pushrod diameter/thickness.
As a matter of fact, most rocker arms have deflection engineered into the design. Check a rocker arm ratio with a checking spring, then go back and check it with the actual spring. If you do this exercise once, you'll think, "Why am I measuring .625" lift when it should be .600"?" Always check your piston valve clearance, rocker geometry, lift at valve, etc., etc., with the actual valve spring and pushrod you're going to use.
Also, always keep each spring locator, retainer, and lock pair with the valve that you checked install height with. Locks can vary by a few thou, as well as retainers and locators. I always go through and measure each one, then line them up in a row the way they will be assembled.
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Can i ask what is best way to measure valve travel when hyd roller or hyd flat lifters are going to be used?
Is it safe to bottom out the lifter when a adjustable rocker is used or will that effect geometry to much and give a false valve lift number?
Joel
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Can i ask what is best way to measure valve travel when hyd roller or hyd flat lifters are going to be used?
Is it safe to bottom out the lifter when a adjustable rocker is used or will that effect geometry to much and give a false valve lift number?
Joel
If you are talking checking for valve clearance, most of us have a solid lifter to use with an adjustable pushrod, however, I also have a few slugs that I have made to fit the top of a hyd lifter, which makes things easy too. Regardless, you will get more lift with a checking spring than you will with a real spring, but it's worst case, and so much easier LOL
I probably wouldn't trust bottoming the lifter as you can't really see what is going on inside, and with a checking spring, it wouldn't bottom anyway. In theory it would work, but so easy to do it other ways, it's not really worth it.
FYI, I used a flange headed bolt to make my slugs, ground the head down to fit the ID of the top of the lifter body, flange sits on the surface, then partially drilled a locating hole for the pushrod. Think upside down hat. 10 minutes on a bench grinder. Works well and cheap