Lifter Collapse During Preload

Joe Scrivens

Member
Aug 27, 2014
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Hello all.

So I am still not satisfied with my valve-train geometry.

I have checked rand rechecked.

went through 3 sets of pushrods and recently someone said ONE WORD to me that might be my problem.

Well two words actually. Lifter Collapse.

I may be encountering lifter collapse during pushrod length checking.

This is crucial to my finding out the right pushrod length.

I took that into account and also crunched some numbers.

my pushrods MIGHT be 0.100 to 0.150 too long.

My mathematics are as follows

if stock mustangs pushrods are 6.250 in length and I have 6.350 push rods now I am 0.100 too long.

my cylinder head has been milled two times equaling out to .060 shaved off meaning I am now 0.160 too long in length.

I also have the flatter Fel Pro gaskets on there which may be 0.010 to 0.025 less deck height equating to a grand total of 0.175 too long on the push rod side.

my actual reason for this post is not solely showing off my abilities in addition =P but rather an inquiry on a possible solution.

I have been told and read that i should "shim" my rockers to the necessary amount to correct the geometry. well now to get +/- 0.175 height in shims is actually quite silly since i would be using roughly 5 or so shims.

Would it be plausible to add an ARP washer UNDER the pedestal rail lifting the rocker assembly up 0.150 and them shim once to try and correct the geometry?

In my theory it seems like a simpler and cost effective fix than buying a new set of magnum pushrods, since all I will be doing in reality is mimicing the lost deck height under the pedestal rockers.
 
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Are you installing the rockers on E7 heads? They make an adjustable push rod tool to measure push rod length, are you not using one or are you guessing from the math your using starting with stock length rods to order these push rods?

What cam and valve springs?

To answer your question I would get the correct length push rod. Shims are made to make up small variances in the valve train, not to correct the wrong push rod length by too large of a margin. So if you need 6.25" then go get'em.
 
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What is the process that you used to measure the original pushrods? When you say that the geometry is wrong, are you talking about the swipe of the rocker tip is not centered on the valve stem?
 
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Are you installing the rockers on E7 heads? They make an adjustable push rod tool to measure push rod length, are you not using one or are you guessing from the math your using starting with stock length rods to order these push rods?

What cam and valve springs?

To answer your question I would get the correct length push rod. Shims are made to make up small variances in the valve train, not to correct the wrong push rod length by too large of a margin. So if you need 6.25" then go get'em.
I was using the adjustable pushrod checker but wasn't realizing the lifter was collapsing from the spring tension. Cam is comp cams extreme energy valve springs comp cams dual springs . My thing is I've spent over 500$ on pushrods and always getting different symptoms. Im just trying to figure out preload and using the washers as temporary checking.
 
Is the swipe too far towards the intake or exhaust side of the head? You can run the lifter bottomed out if you had to but I wouldn't recommend it. We did stuff like that years ago when all of the "newer' parts weren't' so available. I hate to say it, but to properly check pushrod length on a hydraulic lifter motor you need to install lighter weight springs as to not bleed the lifter down when you roll the motor over
 
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Is the swipe too far towards the intake or exhaust side of the head? You can run the lifter bottomed out if you had to but I wouldn't recommend it. We did stuff like that years ago when all of the "newer' parts weren't' so available. I hate to say it, but to properly check pushrod length on a hydraulic lifter motor you need to install lighter weight springs as to not bleed the lifter down when you roll the motor over

yea sounds like what I need to do to satisfy my need to "know"

the car runs and runs great from my opinion, i just dont appreciate the ever weary feeling that if I get to over 5k rpm Ill valve float it.

thanks!
 
The orientation of the swipe on the valve tip will have little to no effect on valve float. Valve float will have more to do with spring pressures. Can you post a picture of the swipe pattern on your valve stem?
 
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Math is math. 6.272" stock length pushrods, on stock heads. Assuming you milled stock heads, and you are 100% sure that they were milled .060, it would be like putting 6.332" pushrods in a completely stock set up. That could be shimmed out. You said your current pushrods are 6.350". So with the milled .060, it would be like having 6.410" pushrods in a completely stock, non milled system. So, options are 1) valve with shorter stems, 2) correct length pushrods (6.212") 3) Take a random chance trying to find washers that are .198" in thickness with your current pushrods. I would order the right pushrods. Its going to be the fastest and most correct method to set your valve train up.
 
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Math is math. 6.272" stock length pushrods, on stock heads. Assuming you milled stock heads, and you are 100% sure that they were milled .060, it would be like putting 6.332" pushrods in a completely stock set up. That could be shimmed out. You said your current pushrods are 6.350". So with the milled .060, it would be like having 6.410" pushrods in a completely stock, non milled system. So, options are 1) valve with shorter stems, 2) correct length pushrods (6.212") 3) Take a random chance trying to find washers that are .198" in thickness with your current pushrods. I would order the right pushrods. Its going to be the fastest and most correct method to set your valve train up.
Math is math. 6.272" stock length pushrods, on stock heads. Assuming you milled stock heads, and you are 100% sure that they were milled .060, it would be like putting 6.332" pushrods in a completely stock set up. That could be shimmed out. You said your current pushrods are 6.350". So with the milled .060, it would be like having 6.410" pushrods in a completely stock, non milled system. So, options are 1) valve with shorter stems, 2) correct length pushrods (6.212") 3) Take a random chance trying to find washers that are .198" in thickness with your current pushrods. I would order the right pushrods. Its going to be the fastest and most correct method to set your valve train up.

:bang:

Now i don't even know if the valves on there are already shorter stems...

the heads were worked on before I got them and came with teh valves... how do I measure the valves to see if they have the shorter stems or not?

My idea with the washers was a temporary. lik ei mean just starting it up to see if the sewing machine sound goes away or if it seriously just the cam sound of the valves slapping closed.

3

if the washers Idea solves the problem for preloading then i will know the pushrod length is the culprit and order the shorter ones.

i have the stock 6.248 pushrods in my garage but they are the ball tip ones. i never trusted those. i only use the Magnum pushrods one piece.
 
Math is math. 6.272" stock length pushrods, on stock heads. Assuming you milled stock heads, and you are 100% sure that they were milled .060, it would be like putting 6.332" pushrods in a completely stock set up. That could be shimmed out. You said your current pushrods are 6.350". So with the milled .060, it would be like having 6.410" pushrods in a completely stock, non milled system. So, options are 1) valve with shorter stems, 2) correct length pushrods (6.212") 3) Take a random chance trying to find washers that are .198" in thickness with your current pushrods. I would order the right pushrods. Its going to be the fastest and most correct method to set your valve train up.
All of this is assuming that the deck height on the block is the same as the next engine. That is usually not the case. From the factory the tolerances where good enough for them to just put these motors together. I have seen two identical casting number blocks side by side that both measure deck heights that are .080 different. The math is fine and all, but you need to measure to check. This is the only way to be sure
 
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I agree 100%. Measuring is the absolutely correct way. The math was just to give an idea of how far off the numbers are now compared to what it was stock. I honestly didn't take deck height into consideration. I presumed tolerances were a lot tighter.

I can see where you are going with the washer. Using a washer and trial and error system keeps you from having to swap out the springs. You can do it with the head on, and it would allow you to then use the measuring tool in order to get the proper rod length.
 
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All of this is assuming that the deck height on the block is the same as the next engine. That is usually not the case. From the factory the tolerances where good enough for them to just put these motors together. I have seen two identical casting number blocks side by side that both measure deck heights that are .080 different. The math is fine and all, but you need to measure to check. This is the only way to be sure

thats crazy.

you would think big companies would be able to reproduce exact replicas every single time by now...
 
I agree 100%. Measuring is the absolutely correct way. The math was just to give an idea of how far off the numbers are now compared to what it was stock. I honestly didn't take deck height into consideration. I presumed tolerances were a lot tighter.

I can see where you are going with the washer. Using a washer and trial and error system keeps you from having to swap out the springs. You can do it with the head on, and it would allow you to then use the measuring tool in order to get the proper rod length.

cool I just wanted to make sure the washer idea wouldn't create some other problems that would give incorrect measurements lol
 
I lost something here. I was saying you can swap the springs out w/o pulling the head. Compressed air in the cylinder to hold the valves up and a compression tool to remove the springs.

The washer idea may or may not work. There is the assumption that you are going to find 16 washers with the exact same thickness. Also finding 16 washers that are damn close to 0.198" in thickness so you can be close to where you need to be to start adjusting. It wont cause any more issues that what you are currently in. It seems easier to swap the springs and measure the one time vs. adding washers and assembling and disassembling multiple times.
 
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I lost something here. I was saying you can swap the springs out w/o pulling the head. Compressed air in the cylinder to hold the valves up and a compression tool to remove the springs.

The washer idea may or may not work. There is the assumption that you are going to find 16 washers with the exact same thickness. Also finding 16 washers that are damn close to 0.198" in thickness so you can be close to where you need to be to start adjusting. It wont cause any more issues that what you are currently in. It seems easier to swap the springs and measure the one time vs. adding washers and assembling and disassembling multiple times.

i did find these:
http://www.summitracing.com/parts/arp-200-8586

:trollface:
 
You beat me to it. Precision ground washers are the way to go in this scenario. For what its worth, under one side of my shaft rockers I have .200 tall washers to adjust the stand height for proper geometry and the other head has .250 tall washers to achieve the same geometry. The block is parallel decked but the machining in the cylinder heads has a slight variation from one side to another. I have spun this motor past 8,700rpms and no issues. The right type of washer is paramount.
 
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You beat me to it. Precision ground washers are the way to go in this scenario. For what its worth, under one side of my shaft rockers I have .200 tall washers to adjust the stand height for proper geometry and the other head has .250 tall washers to achieve the same geometry. The block is parallel decked but the machining in the cylinder heads has a slight variation from one side to another. I have spun this motor past 8,700rpms and no issues. The right type of washer is paramount.

Hey thanks!

I just have one more question.

Can the washers be Grade 8 or must they be made from Hardened Chromoly?

I know Homedepot has Grade 8 Zinc Plated washers. would the zinc coating cause a problem or should i actually wait till i place an order for the ARP's?

thanks!
 
Hey thanks!

I just have one more question.

Can the washers be Grade 8 or must they be made from Hardened Chromoly?

I know Homedepot has Grade 8 Zinc Plated washers. would the zinc coating cause a problem or should i actually wait till i place an order for the ARP's?

thanks!
Nothing at home depot is going to work for you. The washers very specifically need to be precision ground with a very small tolerance as to thickness. Most precision ground stuff will have a variation of no more than +/- .001
 
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