HR Closed Spring Pressure Question
12-11-2004, 04:26 PM
#1
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HR Closed Spring Pressure Question
For small HRs like the Crane 227, CC304, GM845, etc. what is an acceptable
maximum closed spring pressure with Comp R lifters? How much would this
need to be reduced for stock lifters? Also, what is an acceptable maximum
spring rate?
To qualify the question a bit, I am looking for the acceptable maximum that
would apply for a daily driver car (good longevity).
maximum closed spring pressure with Comp R lifters? How much would this
need to be reduced for stock lifters? Also, what is an acceptable maximum
spring rate?
To qualify the question a bit, I am looking for the acceptable maximum that
would apply for a daily driver car (good longevity).
12-12-2004, 10:55 AM
#2
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Location: Upstate NY
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Re: HR Closed Spring Pressure Question
Originally Posted by truedualws6
For small HRs like the Crane 227, CC304, GM845, etc. what is an acceptable
maximum closed spring pressure with Comp R lifters? How much would this
need to be reduced for stock lifters? Also, what is an acceptable maximum
spring rate?
To qualify the question a bit, I am looking for the acceptable maximum that
would apply for a daily driver car (good longevity).
maximum closed spring pressure with Comp R lifters? How much would this
need to be reduced for stock lifters? Also, what is an acceptable maximum
spring rate?
To qualify the question a bit, I am looking for the acceptable maximum that
would apply for a daily driver car (good longevity).
There is no magic number.
If you are designing a valvetrain, choose the spring that compliments the rest of the bits so that the valve is controlled thruout the entire rev range. That does not necessarily mean high spring pressure. For example, some of the beehive springs with lightweight retainers can controll your HR system with much less total spring pressure than conventional springs will require.
If you have someone designing your valvetrain, he should look at all your requirements and specify the spring that does the job. That service may be free at a cam manufacturer's tech line, but it may not be optimum. You may need to pay for the advice or buy the components from the advisor.
12-12-2004, 03:09 PM
#4
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Re: HR Closed Spring Pressure Question
Originally Posted by OldSStroker
If you are designing a valvetrain, choose the spring that compliments the rest of the bits so that the valve is controlled thruout the entire rev range.
be a logical first choice?
Originally Posted by OldSStroker
That does not necessarily mean high spring pressure. For example, some of the beehive springs with lightweight retainers can controll your HR system with much less total spring pressure than conventional springs will require..
my dyno graph is float. I have not made any progress by asking questions
in the LT1 Engine Tech board, so it seemed like time to see what you
Advanced Tech types had to say.
You would think the 26915s would work in my setup. Stock heads, 227 cam,
7/16 studs, comp pro mag 1.6s, comp Rs, and a 1.75" installed height. Before
the cam install I ran the LT4 springs with the 1.6 rockers with no problems
at all and they are about 20# less closed pressure with a similar open pressure.
12-12-2004, 04:05 PM
#5
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Re: HR Closed Spring Pressure Question
What is advertised on spring pressure is not revelant after a few miles.
I get a spring that advertises at 150# on the seat and 350# on the nose. They will loose some pressure after a few heat cycles about 20-25lbs so if you have less than this it is doughtful you have enough. It makes no difference to a hyd lifter what pressure you run (within reason-not 275&700) it will operate the same(stock or aftermarket). Stock lifters will do just fine with the pressures above and even more pressure. Where you get in trouble with hyd's is to little pressure and the valve floating or bounceing off of the seat.The lifter will do what it's suppose to do and take up the slack and hold the valve open.A lot of people think "bounce" is valve float and they are two different things.In any event you have to have enough spring to cover both. This BS of to much spring costing HP is nuts. How much HP does it cost when the valves don't close right? You have to have enough spring and 0- 1HP ain't s*** if the car runs RIGHT. We ain't trying to run Pro Stock!!!!!!!
I get a spring that advertises at 150# on the seat and 350# on the nose. They will loose some pressure after a few heat cycles about 20-25lbs so if you have less than this it is doughtful you have enough. It makes no difference to a hyd lifter what pressure you run (within reason-not 275&700) it will operate the same(stock or aftermarket). Stock lifters will do just fine with the pressures above and even more pressure. Where you get in trouble with hyd's is to little pressure and the valve floating or bounceing off of the seat.The lifter will do what it's suppose to do and take up the slack and hold the valve open.A lot of people think "bounce" is valve float and they are two different things.In any event you have to have enough spring to cover both. This BS of to much spring costing HP is nuts. How much HP does it cost when the valves don't close right? You have to have enough spring and 0- 1HP ain't s*** if the car runs RIGHT. We ain't trying to run Pro Stock!!!!!!!
Last edited by 1racerdude; 12-12-2004 at 04:11 PM.
12-12-2004, 04:58 PM
#6
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Location: Perryopolis, Pa
Posts: 520
Re: HR Closed Spring Pressure Question
Here are a few things worth mentioning.....
1. The cam card is the best place to start. No reason to deviate if you are using common components. If you have an odd combination, you may have to experiment.
2. Why are you considering Comp R lifters with a little cam? The stock type should be fine. Small cams do not exhibit the lifter pump up problems like big cams at high RPM & you do not have to run excessive seat pressure that collapses stock lifters.
3. As stated above, springs will lose some tension after break-in. If you are a few # high initially they will drop somewhat & come back into the proper range. I do not recommend over 130# seat pressure to start with. Worst case you have to reshim later.
4. Break your springs in..... Most people do not even realize you should do this.
Start engine & idle for a few minutes. Shut off & let engine cool.
Repeat process.
Then drive for a few miles & keep rpm low, say 3500 or less. Let cool again.
Then for best results put on a 100 more miles before running at max RPM.
This sounds like overkill, but will help the spring life. The springs have time to heat cycle without getting excessively hot. It amazes me how many people start the engine, warm it up & take it out to see how high it revs.
Lastly,
It sounds like you may be overthinking much of this anyway as you are not trying to turn over 6500. If you are, you are looking at too small of cams anyway & then all of the above is more relevant to proper spring selection.
1. The cam card is the best place to start. No reason to deviate if you are using common components. If you have an odd combination, you may have to experiment.
2. Why are you considering Comp R lifters with a little cam? The stock type should be fine. Small cams do not exhibit the lifter pump up problems like big cams at high RPM & you do not have to run excessive seat pressure that collapses stock lifters.
3. As stated above, springs will lose some tension after break-in. If you are a few # high initially they will drop somewhat & come back into the proper range. I do not recommend over 130# seat pressure to start with. Worst case you have to reshim later.
4. Break your springs in..... Most people do not even realize you should do this.
Start engine & idle for a few minutes. Shut off & let engine cool.
Repeat process.
Then drive for a few miles & keep rpm low, say 3500 or less. Let cool again.
Then for best results put on a 100 more miles before running at max RPM.
This sounds like overkill, but will help the spring life. The springs have time to heat cycle without getting excessively hot. It amazes me how many people start the engine, warm it up & take it out to see how high it revs.
Lastly,
It sounds like you may be overthinking much of this anyway as you are not trying to turn over 6500. If you are, you are looking at too small of cams anyway & then all of the above is more relevant to proper spring selection.
12-13-2004, 12:02 AM
#7
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Join Date: Jan 2004
Location: Downey, CA
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Re: HR Closed Spring Pressure Question
The information provided so far is much appreciated. What I am trying to
do is way small potatoes compared to most cars on this board. I can't even
say my car is a race car, it's just plain mild by comparison. Whatever is going
on seems to be the result of mixing lots of parts.
I had no idea springs would lose 20+ pounds after a few heat cycles. That is
good to know. The spring break in makes sense and luckily, I did the right thing,
but more so to break in the cam, lifters, timing chain, etc. I did several heat
cycles and also ran well below 3,500 rpm for the first 200 miles. The only reason
for going with the Comp Rs was to run new parts and they seemed to be the
recommended choice. I could have reused the stock lifters, but it was not about
saving a few bucks.
Even though it would be easiest to replace the 26915s with 26918s, I'm not
real keen on the idea. At 1.75" installed height the closed pressure will be
around 145#, with an open pressure in the 320# range. The spring from the
cam card is the Crane 99893 (dual) that would be 145# at 1.78" installed
height, and 380# open, which seemed like a lot more pressure than necessary.
Another dual spring option is the Comp 987 which is used in a lot of LT1
applications. These are 130# closed and 330# open for my setup.
Of course this is all assuming that my problem is the 26915s. If this is the case
then is it valve float or lifter bounce. And where is the spring pressure problem,
in the closed, open, or both areas?
As for overthinking things, the answer is definately yes. But one look at the dyno
curve and it's a reasonable quest, even for a basically stock car. I think that
everyone wants their car to run the best it can. This may even be worth 10+
rwhp once it's resolved.
do is way small potatoes compared to most cars on this board. I can't even
say my car is a race car, it's just plain mild by comparison. Whatever is going
on seems to be the result of mixing lots of parts.
I had no idea springs would lose 20+ pounds after a few heat cycles. That is
good to know. The spring break in makes sense and luckily, I did the right thing,
but more so to break in the cam, lifters, timing chain, etc. I did several heat
cycles and also ran well below 3,500 rpm for the first 200 miles. The only reason
for going with the Comp Rs was to run new parts and they seemed to be the
recommended choice. I could have reused the stock lifters, but it was not about
saving a few bucks.
Even though it would be easiest to replace the 26915s with 26918s, I'm not
real keen on the idea. At 1.75" installed height the closed pressure will be
around 145#, with an open pressure in the 320# range. The spring from the
cam card is the Crane 99893 (dual) that would be 145# at 1.78" installed
height, and 380# open, which seemed like a lot more pressure than necessary.
Another dual spring option is the Comp 987 which is used in a lot of LT1
applications. These are 130# closed and 330# open for my setup.
Of course this is all assuming that my problem is the 26915s. If this is the case
then is it valve float or lifter bounce. And where is the spring pressure problem,
in the closed, open, or both areas?
As for overthinking things, the answer is definately yes. But one look at the dyno
curve and it's a reasonable quest, even for a basically stock car. I think that
everyone wants their car to run the best it can. This may even be worth 10+
rwhp once it's resolved.
Last edited by truedualws6; 12-13-2004 at 12:06 AM.
12-13-2004, 12:35 AM
#8
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Join Date: May 2003
Location: LA (lower Alabama)
Posts: 6,661
Re: HR Closed Spring Pressure Question
Originally Posted by truedualws6
The information provided so far is much appreciated. What I am trying to
do is way small potatoes compared to most cars on this board. I can't even
say my car is a race car, it's just plain mild by comparison. Whatever is going
on seems to be the result of mixing lots of parts.
I had no idea springs would lose 20+ pounds after a few heat cycles. That is
good to know. The spring break in makes sense and luckily, I did the right thing,
but more so to break in the cam, lifters, timing chain, etc. I did several heat
cycles and also ran well below 3,500 rpm for the first 200 miles. The only reason
for going with the Comp Rs was to run new parts and they seemed to be the
recommended choice. I could have reused the stock lifters, but it was not about
saving a few bucks.
Some loose more.
Even though it would be easiest to replace the 26915s with 26918s, I'm not
real keen on the idea. At 1.75" installed height the closed pressure will be
around 145#, with an open pressure in the 320# range. The spring from the
cam card is the Crane 99893 (dual) that would be 145# at 1.78" installed
height, and 380# open, which seemed like a lot more pressure than necessary.
Another dual spring option is the Comp 987 which is used in a lot of LT1
applications. These are 130# closed and 330# open for my setup.
Take 20-25# of of that and what do you have.
Of course this is all assuming that my problem is the 26915s. If this is the case
then is it valve float or lifter bounce. And where is the spring pressure problem,
in the closed, open, or both areas?
It isn't lifter bounce,it's valve bounce caused when there isn't enough pressure to control the valve.
As for overthinking things, the answer is definately yes. But one look at the dyno
curve and it's a reasonable quest, even for a basically stock car. I think that
everyone wants their car to run the best it can. This may even be worth 10+
rwhp once it's resolved.
do is way small potatoes compared to most cars on this board. I can't even
say my car is a race car, it's just plain mild by comparison. Whatever is going
on seems to be the result of mixing lots of parts.
I had no idea springs would lose 20+ pounds after a few heat cycles. That is
good to know. The spring break in makes sense and luckily, I did the right thing,
but more so to break in the cam, lifters, timing chain, etc. I did several heat
cycles and also ran well below 3,500 rpm for the first 200 miles. The only reason
for going with the Comp Rs was to run new parts and they seemed to be the
recommended choice. I could have reused the stock lifters, but it was not about
saving a few bucks.
Some loose more.
Even though it would be easiest to replace the 26915s with 26918s, I'm not
real keen on the idea. At 1.75" installed height the closed pressure will be
around 145#, with an open pressure in the 320# range. The spring from the
cam card is the Crane 99893 (dual) that would be 145# at 1.78" installed
height, and 380# open, which seemed like a lot more pressure than necessary.
Another dual spring option is the Comp 987 which is used in a lot of LT1
applications. These are 130# closed and 330# open for my setup.
Take 20-25# of of that and what do you have.
Of course this is all assuming that my problem is the 26915s. If this is the case
then is it valve float or lifter bounce. And where is the spring pressure problem,
in the closed, open, or both areas?
It isn't lifter bounce,it's valve bounce caused when there isn't enough pressure to control the valve.
As for overthinking things, the answer is definately yes. But one look at the dyno
curve and it's a reasonable quest, even for a basically stock car. I think that
everyone wants their car to run the best it can. This may even be worth 10+
rwhp once it's resolved.
Most of the stories you hear about factory lifter's are caused by springs.
12-13-2004, 09:11 AM
#11
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Re: HR Closed Spring Pressure Question
Originally Posted by 1racerdude
Read between the paragraphs of your post I quoted.
are the ticket. Too bad I did not do it originally. As for the beehives, are you
saying that they lose more pressure than the average, or just that some springs
lose more than others?
My plan if I run the 99893 springs is to use L98 seats and the Comp 730-16
titanium retainers (I have the seats and retainers in stock). Others have
verified that this combination works. Does it matter if the OD of the seat is
smaller than the OD of the outer spring? The L98 seat is about 1.35" and
the 99893 is 1.46".
12-13-2004, 11:31 AM
#12
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Join Date: Oct 2002
Posts: 6,518
Re: HR Closed Spring Pressure Question
The 26918's would probably be a good spring to try for your setup.
Spring pressure is always your friend when valve control is needed and the Comp R's can take a TON of spring pressure.
Bret
Spring pressure is always your friend when valve control is needed and the Comp R's can take a TON of spring pressure.
Bret
12-15-2004, 12:01 AM
#13
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Re: HR Closed Spring Pressure Question
Originally Posted by SStrokerAce
The 26918's would probably be a good spring to try for your setup.
Bret
Bret
Now that I have read everything I can search up or get my hands on regarding
springs, I'm wondering about the advantages of dual springs from a safety
standpoint. If a spring fails there is another to keep from having carnage.
If it's not about the cost and more so about the overall reliability and durability
of the setup, is a dual spring better than a single?
12-15-2004, 12:20 AM
#14
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Location: LA (lower Alabama)
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Re: HR Closed Spring Pressure Question
Originally Posted by truedualws6
I did and thanks. It's looking like the springs Crane recommends for the cam
are the ticket. Too bad I did not do it originally. As for the beehives, are you
saying that they lose more pressure than the average, or just that some springs
lose more than others?
My plan if I run the 99893 springs is to use L98 seats and the Comp 730-16
titanium retainers (I have the seats and retainers in stock). Others have
verified that this combination works. Does it matter if the OD of the seat is
smaller than the OD of the outer spring? The L98 seat is about 1.35" and
the 99893 is 1.46".
are the ticket. Too bad I did not do it originally. As for the beehives, are you
saying that they lose more pressure than the average, or just that some springs
lose more than others?
My plan if I run the 99893 springs is to use L98 seats and the Comp 730-16
titanium retainers (I have the seats and retainers in stock). Others have
verified that this combination works. Does it matter if the OD of the seat is
smaller than the OD of the outer spring? The L98 seat is about 1.35" and
the 99893 is 1.46".
Doesn't matter about the OD as long as you don't have to do a bunch of machine work(money ya know)
A dual spring is always better than a single and one spring will cancel out harmonics on the other.
Just watch your PSI rating and don't go to big.Stay with the 150#-350# unless the cam people recommend a different set of numbers. You have to have retainers for dual springs also.
Most springs will loose the 20-25lb's but there are high dollar springs that don't loose near that much(I'm talking $500-$1000.00 dollars a set) Been using the 20-25lb rule for a number of years and have had good sucess with it.
12-15-2004, 07:03 AM
#15
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Join Date: Oct 2002
Location: Upstate NY
Posts: 2,931
Re: HR Closed Spring Pressure Question
Originally Posted by 1racerdude
Doesn't matter about the OD as long as you don't have to do a bunch of machine work(money ya know)
A dual spring is always better than a single and one spring will cancel out harmonics on the other.
Just watch your PSI rating and don't go to big.Stay with the 150#-350# unless the cam people recommend a different set of numbers. You have to have retainers for dual springs also.
Most springs will loose the 20-25lb's but there are high dollar springs that don't loose near that much(I'm talking $500-$1000.00 dollars a set) Been using the 20-25lb rule for a number of years and have had good sucess with it.
A dual spring is always better than a single and one spring will cancel out harmonics on the other.
Just watch your PSI rating and don't go to big.Stay with the 150#-350# unless the cam people recommend a different set of numbers. You have to have retainers for dual springs also.
Most springs will loose the 20-25lb's but there are high dollar springs that don't loose near that much(I'm talking $500-$1000.00 dollars a set) Been using the 20-25lb rule for a number of years and have had good sucess with it.
One of the reasons beehive springs work so well is that they don't have all the harmonics to cancel out. A big enemy of spring life is heat, and with two springs rubbing together more heat is generated. I've seen some Spintron pictures of dual springs and beehive springs doing their "dances". The beehives were more like a waltz and the duals like a jitterbug (for all us old farts who remember that dance).