Noisey valvetrain (sewing machine)
Skewed #'s Just want to clear up some of the figures quoted on this thread and some others. 1.25 -1.5 turns of the rocker bolt may be the "sweet spot" for lifter preload, not trying to argue that, but it surely isn't .05875" -.0705". Those numbers are what the bolt travels parallel to it's axis, not the travel at the pushrod end of the rocker. We are working on a 1.7:1 rocker arm ratio. So when the bolt is tightened with the valve stationary, for every .047" (1 turn) of bolt movement, the pushrod compresses the lifter plunger .075". A little bit of trigonometry involved to figure the numbers, but it can be easily verified with a dial indicator on the pushrod end of the rocker while tightening.
No offense but I am not what there is to clear up. Shane's way works every good. I checked mine first with pushrod checker the normal way and then used Shane's technique and came up with the same numbers. When a shop has done hundreds and stakes their reputation and good name on delivering a quality reliable product, I will take real world over trig any day.
Just want to clear up some of the figures quoted on this thread and some others. 1.25 -1.5 turns of the rocker bolt may be the "sweet spot" for lifter preload, not trying to argue that, but it surely isn't .05875" -.0705". Those numbers are what the bolt travels parallel to it's axis, not the travel at the pushrod end of the rocker. We are working on a 1.7:1 rocker arm ratio. So when the bolt is tightened with the valve stationary, for every .047" (1 turn) of bolt movement, the pushrod compresses the lifter plunger .075". A little bit of trigonometry involved to figure the numbers, but it can be easily verified with a dial indicator on the pushrod end of the rocker while tightening.
1) The 1.7 ratio refers to how much the valve tip end moves in relation to the pushrod end with a stationary fulcrum point. When doing this the valve tip end is stationary, so you need to relate the amount of movement from the fulcrum point to the pushrod tip, which is not the same 1.7 so your math is off.
2) I don't think he stated that you are moving the fulcrum point .047" like you are using for your math model, he said that one turn equals .047" of preload on the pushrod end, so there was no need for math in the first place.
Trust me, Shane knows how much preload he is getting with his method. If it multiplied the way you are saying, you would bottom the lifter out going as far as alot of people are.
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2 things.
1) The 1.7 ratio refers to how much the valve tip end moves in relation to the pushrod end with a stationary fulcrum point. When doing this the valve tip end is stationary, so you need to relate the amount of movement from the fulcrum point to the pushrod tip, which is not the same 1.7 so your math is off.
2) I don't think he stated that you are moving the fulcrum point .047" like you are using for your math model, he said that one turn equals .047" of preload on the pushrod end, so there was no need for math in the first place.
Trust me, Shane knows how much preload he is getting with his method. If it multiplied the way you are saying, you would bottom the lifter out going as far as alot of people are.
1) The 1.7 ratio refers to how much the valve tip end moves in relation to the pushrod end with a stationary fulcrum point. When doing this the valve tip end is stationary, so you need to relate the amount of movement from the fulcrum point to the pushrod tip, which is not the same 1.7 so your math is off.
2) I don't think he stated that you are moving the fulcrum point .047" like you are using for your math model, he said that one turn equals .047" of preload on the pushrod end, so there was no need for math in the first place.
Trust me, Shane knows how much preload he is getting with his method. If it multiplied the way you are saying, you would bottom the lifter out going as far as alot of people are.
I did state as you did the the valve tip end IS stationary (new fulcrum point when measuring).
Think of it as a lever when you tighten the bolt, the pushrod end of the rocker is going to move further than the bolt is when depressing. The threads are ~.047" apart (1 full rev.), i've seen this figure referenced as the preload amount for 1 revolution of the rocker bolt: Furthermore the "target" is 1.25-1.5 revolutions which is quoted as equalling .059"-.071" of preload. Am I misquoting these claims?
Now, in this case the end of the "lever" is moving ~.075" for every full rev of the rocker bolt.
I've measured it every which way, length checker, mathematically, and dial indicator on the same engine, same valve position, same day. Every one of them validates my statements.
I am not questioning the method, just the specs on the result of the method.
You are simply overthinking it.
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Edit: The 1.7:1 rocker arm ratio is entirely relevant.
You're right I probably am overthinking it, but that was caused by me getting conflicting results when doing my build. The bolt method came out right on the money with my stockers but my length checker and the dial indicator told a different story, so I had to figure out why.
When I realized the rocker bolt method was leading me to preload numbers that didn't make sense based on what i've read on here, I ran the numbers and posted my original post on this thread to clear some things up since I used this thread as a reference for my build using the bolt method.
The original O.P. was having similar frustrations.
Not trying to start a pissing match or "prove" somebody wrong on here, just sharing what I found.
You're right I probably am overthinking it, but that was caused by me getting conflicting results when doing my build. The bolt method came out right on the money with my stockers but my length checker and the dial indicator told a different story, so I had to figure out why.
When I realized the rocker bolt method was leading me to preload numbers that didn't make sense based on what i've read on here, I ran the numbers and posted my original post on this thread to clear some things up since I used this thread as a reference for my build using the bolt method.
The original O.P. was having similar frustrations.
Not trying to start a pissing match or "prove" somebody wrong on here, just sharing what I found.
Its the number of turns times .047
Shane at Thunder Racing gets the credit.
"The TDC method is NOT always accurate. Try the EO/IC method to check pushrod length. I have posted directions on this forum numerous times... Here it is again:
FWIW, EVERY cam install I have done using the LS7 lifter with a cam with greater than .600" lift (read smaller base circle) AND stock heads w/GM MLS gaskets has taken 7.425" pushrods for ~.050"-.060" preload. We measure lifter preload on each and every cam install we do. I have never had a lifter failure nor do we end up with the dreaded "sewing machine" noise.
Its very simple, If you change ANY of the following:
valve sizes, valve job, head milling, thinner/thicker head gaskets, decked block, cam with an altered base circle, etc... YOU MUST CHECK FOR PROPER PUSHROD LENGTH.
I have helped countless numbers of individuals with this process over the phone, via email, and PM's. I've posted the process on at least 3 occasions.
Here it is again in a nutshell:
1. Using the EO/IC method, get the lifter to the base circle of the cam.
2. Using a known length pushrod (7.400" is a good start with stock rockers) run the rocker arm bolt down to zero lash. This is easily done with your fingers "wiggling" the rocker, the point at which the "slack" is just gone is zero lash.
3. Set your torque wrench to 22 lb./ft. Tighten the rocker to full torque and count the number of turns it takes to get there. 1 full turn wtih a stock 8mm X 1.25 bolt is ~.047" preload as measured at the pushrod/rocker interface.
4. I normally shoot for 1 1/4 to 1 3/4 turns with stock type lifters like Comp 850's, LS1, LS7 etc.
For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter...
I might not know everything but I will tell you that this method has worked for me year after year cam swap after cam swap. We average 3 cam swaps a week here so you can do the math.
If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve.
THIS METHOD ALWAYS WORKS!!!
Check it using the above method and see where you are."
Thanks,
Shane
Shane at Thunder Racing gets the credit.
"The TDC method is NOT always accurate. Try the EO/IC method to check pushrod length. I have posted directions on this forum numerous times... Here it is again:
FWIW, EVERY cam install I have done using the LS7 lifter with a cam with greater than .600" lift (read smaller base circle) AND stock heads w/GM MLS gaskets has taken 7.425" pushrods for ~.050"-.060" preload. We measure lifter preload on each and every cam install we do. I have never had a lifter failure nor do we end up with the dreaded "sewing machine" noise.
Its very simple, If you change ANY of the following:
valve sizes, valve job, head milling, thinner/thicker head gaskets, decked block, cam with an altered base circle, etc... YOU MUST CHECK FOR PROPER PUSHROD LENGTH.
I have helped countless numbers of individuals with this process over the phone, via email, and PM's. I've posted the process on at least 3 occasions.
Here it is again in a nutshell:
1. Using the EO/IC method, get the lifter to the base circle of the cam.
2. Using a known length pushrod (7.400" is a good start with stock rockers) run the rocker arm bolt down to zero lash. This is easily done with your fingers "wiggling" the rocker, the point at which the "slack" is just gone is zero lash.
3. Set your torque wrench to 22 lb./ft. Tighten the rocker to full torque and count the number of turns it takes to get there. 1 full turn wtih a stock 8mm X 1.25 bolt is ~.047" preload as measured at the pushrod/rocker interface.
4. I normally shoot for 1 1/4 to 1 3/4 turns with stock type lifters like Comp 850's, LS1, LS7 etc.
For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter...
I might not know everything but I will tell you that this method has worked for me year after year cam swap after cam swap. We average 3 cam swaps a week here so you can do the math.
If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve.
THIS METHOD ALWAYS WORKS!!!
Check it using the above method and see where you are."
Thanks,
Shane
I appreciate your math efforts as I myself was a math major in college (didn't see that coming from a parts slinger I bet). I think the only problem is that you assumed the need to calculate a variable when it was assigned a value in the original problem. It is an obvious and simple notion that you are proposing and it is very correct, one end moves further than the bolt, but he says he measured it at the pushrod tip and not the bolt.
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Last edited by Scoggin Dickey; Feb 11, 2010 at 01:37 PM.
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As you quoted- the rocker bolt is a 8mm x 1.25mm.
This means that the thread to thread distance equals 1.25mm, equivilant to .049212***** inches. This means that with every rotation of the bolt, it moves approximately .049", but let's call it .047" for a constant cuz that's insignificant at the moment.
Since this is not a 1:1 ratio for bolt to pushrod movement, it CANNOT possibly equal .047" of lifter preload- there's just no way.
I come up with .075" (rounded) of pushrod movement with every bolt turn due to the compounded action of the lever using the 1.7 (fulcrum to bolt location):1(bolt location to pushrod location) ratio. If the bolt were closer to the fulcrum, the pushrod would move ever further with every bolt rev and vis versa if it were closer to the pushrod end.
The math doesn't add up- literally. This drove me crazy when doing my measurements at first cuz I wanted to make damn sure the thing didn't end up sounding like a chinese sweater factory when I was done.
I used LS7 lifters and was shooting for .050-.060" of lifter preload, the bolt method was way off when I was getting 1.25 turns from zero lash to 22 ft. lbs. and the above stated is precisely why.
I drew a little picture (not to scale of course, it's just paint), not to insult, just to help me describe my words.
This means that the thread to thread distance equals 1.25mm, equivilant to .049212***** inches. This means that with every rotation of the bolt, it moves approximately .049", but let's call it .047" for a constant cuz that's insignificant at the moment.
Since this is not a 1:1 ratio for bolt to pushrod movement, it CANNOT possibly equal .047" of lifter preload- there's just no way.
I come up with .075" (rounded) of pushrod movement with every bolt turn due to the compounded action of the lever using the 1.7 (fulcrum to bolt location):1(bolt location to pushrod location) ratio. If the bolt were closer to the fulcrum, the pushrod would move ever further with every bolt rev and vis versa if it were closer to the pushrod end.
The math doesn't add up- literally. This drove me crazy when doing my measurements at first cuz I wanted to make damn sure the thing didn't end up sounding like a chinese sweater factory when I was done.
I used LS7 lifters and was shooting for .050-.060" of lifter preload, the bolt method was way off when I was getting 1.25 turns from zero lash to 22 ft. lbs. and the above stated is precisely why.
I drew a little picture (not to scale of course, it's just paint), not to insult, just to help me describe my words.
He measured it at the pushrod and not the bolt, real world results not a math model with incorrect assumptions. The 1.7 is still the wrong number to use to calculate the pushrod end even if you were to do it using math.
This is using YOUR math model. The static in your equation is the valve end, it remains constant. That is the end that is 1.7 as you stated. When you reach 0 lash, we will consider the rocker arm a straight line. O at the valve tip, 0 at the bolt location, 0 at the pushrod. When you take the bolt down a certain distance, we will maintain the number .047", the pushrod will go down the same distance. That is because it is the 1:1 end as you yourself said so they will remain the same in relation to each other. It is the valve end that the 1.7 is relevant to not the pushrod end. Your own math says you are wrong when you apply the 1.7 to the correct end of the rocker arm.
That doesn't work anyways because you are moving the fulcrum so the 1:1 and 1:7 number are to be slightly modified if you want exact numbers. Regardless, you are applying the 1:7 ratio to the 1:1 end of the rocker arm.
This is a nice friendly discussion and I appreciate that it has maintained civility, but I must bow out of it at this point.
This is using YOUR math model. The static in your equation is the valve end, it remains constant. That is the end that is 1.7 as you stated. When you reach 0 lash, we will consider the rocker arm a straight line. O at the valve tip, 0 at the bolt location, 0 at the pushrod. When you take the bolt down a certain distance, we will maintain the number .047", the pushrod will go down the same distance. That is because it is the 1:1 end as you yourself said so they will remain the same in relation to each other. It is the valve end that the 1.7 is relevant to not the pushrod end. Your own math says you are wrong when you apply the 1.7 to the correct end of the rocker arm.
That doesn't work anyways because you are moving the fulcrum so the 1:1 and 1:7 number are to be slightly modified if you want exact numbers. Regardless, you are applying the 1:7 ratio to the 1:1 end of the rocker arm.
This is a nice friendly discussion and I appreciate that it has maintained civility, but I must bow out of it at this point.
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He measured it at the pushrod and not the bolt, real world results not a math model with incorrect assumptions. The 1.7 is still the wrong number to use to calculate the pushrod end even if you were to do it using math.
This is using YOUR math model. The static in your equation is the valve end, it remains constant. That is the end that is 1.7 as you stated. When you reach 0 lash, we will consider the rocker arm a straight line. O at the valve tip, 0 at the bolt location, 0 at the pushrod. When you take the bolt down a certain distance, we will maintain the number .047", the pushrod will go down the same distance. That is because it is the 1:1 end as you yourself said so they will remain the same in relation to each other. It is the valve end that the 1.7 is relevant to not the pushrod end. Your own math says you are wrong when you apply the 1.7 to the correct end of the rocker arm.
That doesn't work anyways because you are moving the fulcrum so the 1:1 and 1:7 number are to be slightly modified if you want exact numbers. Regardless, you are applying the 1:7 ratio to the 1:1 end of the rocker arm.
This is a nice friendly discussion and I appreciate that it has maintained civility, but I must bow out of it at this point.
This is using YOUR math model. The static in your equation is the valve end, it remains constant. That is the end that is 1.7 as you stated. When you reach 0 lash, we will consider the rocker arm a straight line. O at the valve tip, 0 at the bolt location, 0 at the pushrod. When you take the bolt down a certain distance, we will maintain the number .047", the pushrod will go down the same distance. That is because it is the 1:1 end as you yourself said so they will remain the same in relation to each other. It is the valve end that the 1.7 is relevant to not the pushrod end. Your own math says you are wrong when you apply the 1.7 to the correct end of the rocker arm.
That doesn't work anyways because you are moving the fulcrum so the 1:1 and 1:7 number are to be slightly modified if you want exact numbers. Regardless, you are applying the 1:7 ratio to the 1:1 end of the rocker arm.
This is a nice friendly discussion and I appreciate that it has maintained civility, but I must bow out of it at this point.
Second, You repeated my true statement that the valve end is the static end, then YOU go on to say that you are moving the fulcrum- contradiction.
Third, the 1.7 ratio IS represented by the distance from valve tip of rocker to bolt, which I stated multiple times and illustrated, not the "wrong end" as you say.
Finally, given that fact, there is simply NO WAY the rocker bolt travel and pushrod travel can be equal! Period.
Bottom line, your entire last statement was an attempt to debunk my claims using misconscrewed figures and misquoted words, you didn't understand what I said. Go try measuring it yourself using a dial indicator instead of quoting what somebody else said they did.
Thanks for your input and points of view, I respect you and the company you represent for it. But I do not agree with anyone who says rocker bolt travel and pushrod travel are equal amounts.
I'm done here. Not trying to "convince" anyone, I know what I found, proved it, then shared.
Last edited by SGT20; Feb 11, 2010 at 04:45 PM.
Why can't you just accept that this is a proven Method. Nothing more. It has been used and proven to work for someone who does not have a pushrod checker. Pretty simple to understand.
I tried it several times and it was accurate, like I said, I used the pushrod checker first and later tried this and it flat out worked. You obviously did something wrong. But I won't be able to "convince" you of that either.
I tried it several times and it was accurate, like I said, I used the pushrod checker first and later tried this and it flat out worked. You obviously did something wrong. But I won't be able to "convince" you of that either.
First off, I DID NOT say the pushrod and rocker bolt travel maintain a 1:1 ratio.
Second, You repeated my true statement that the valve end is the static end, then YOU go on to say that you are moving the fulcrum- contradiction.
Third, the 1.7 ratio IS represented by the distance from valve tip of rocker to bolt, which I stated multiple times and illustrated, not the "wrong end" as you say.
Finally, given that fact, there is simply NO WAY the rocker bolt travel and pushrod travel can be equal! Period.
Bottom line, your entire last statement was an attempt to debunk my claims using misconscrewed figures and misquoted words, you didn't understand what I said. Go try measuring it yourself using a dial indicator instead of quoting what somebody else said they did.
Thanks for your input and points of view, I respect you and the company you represent for it. But I do not agree with anyone who says rocker bolt travel and pushrod travel are equal amounts.
I'm done here. Not trying to "convince" anyone, I know what I found, proved it, then shared.
Second, You repeated my true statement that the valve end is the static end, then YOU go on to say that you are moving the fulcrum- contradiction.
Third, the 1.7 ratio IS represented by the distance from valve tip of rocker to bolt, which I stated multiple times and illustrated, not the "wrong end" as you say.
Finally, given that fact, there is simply NO WAY the rocker bolt travel and pushrod travel can be equal! Period.
Bottom line, your entire last statement was an attempt to debunk my claims using misconscrewed figures and misquoted words, you didn't understand what I said. Go try measuring it yourself using a dial indicator instead of quoting what somebody else said they did.
Thanks for your input and points of view, I respect you and the company you represent for it. But I do not agree with anyone who says rocker bolt travel and pushrod travel are equal amounts.
I'm done here. Not trying to "convince" anyone, I know what I found, proved it, then shared.
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You can do this mathematically very easy but 1.7 is not the ratio that you would multiply the bolt movement by. When you are tightening the rocker arm down the pivot point is actually the valve stem not the bolt. So with that said to do this mathematically you would need the distance from the center of the bolt to the valve stem and the distance from the pushrod to the center of the bolt to create a triangle to calculate how the movement of the bolt affects the movement of the pushrod. Then you would have to calculate the angle change at the valve stem to accurately use trig to calculate the pushrod change. Maybe there is a simpler way that I'm overlooking but mathematically takes alot of measureing to have known data to go off of and since measurements must need to be taken place then it's easier to just make one measurement and that's the pushrod depth change from zero lash to 22ftlb torqued.
Basically the 1.7 ratio goes out the window when you change the pivot point.
Just use the proven method or a dial indicator to physically measure it instead of racking your brain with trig questions.
Basically the 1.7 ratio goes out the window when you change the pivot point.
Just use the proven method or a dial indicator to physically measure it instead of racking your brain with trig questions.
Last edited by LSxPwrDZ; Feb 12, 2010 at 04:38 AM.
I'm no lifter guru but I would think it would have something to do with the pressure the internal spring has along with the efficiency range of the oil pressure inside the lifter to hold the pushrod up. Like I said I don't know the in's and outs just speculating.
Anyone have the right answer?
Anyone have the right answer?
I'm no lifter guru but I would think it would have something to do with the pressure the internal spring has along with the efficiency range of the oil pressure inside the lifter to hold the pushrod up. Like I said I don't know the in's and outs just speculating.
Anyone have the right answer?
Anyone have the right answer?