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One of my friends installed a stage 4 cam on his ls3 engine at a local shop, we have provided all the parts. We asked the shop to measure each pushrod so we could buy the correct length, but he didn't. He insisted that there is no possible way that there would be 0.01" variation between each pushrod, and he only measured one intake one exhaust and called it a day. He installed 7.500 pushrods in all cylinders and said that this is the correct length, so my friend touched one of the rocker arms, and it was loose. He was shocked, so he took an adjustable pushrod and checked 7.525 lengths and said that 7.550 is the correct size. I'm not sure if that is true or not, as he does not carry 7.525, and he probably just went with the next size.
Anyway, we talked with a couple of nearby shops, and they said that they couldn't get any more accurate than 0.025 with an adjustable pushrod, and they recommended we buy an adjustable rocker, so we don't have to measure.
We have tested the car for a couple of hundreds of miles and did a wot pull, and the afr was fluctuating so bad like its misfiring I assume some valves do not fully close.
So I started thinking about how we could solve this issue, and these are the ideas I came up with. First, we bought 7.475, 7.500, 7.525, and we already have 7.550. We will try them all and find out which size is too short and which one is zero lash and if all pushrods are roughly the same length and there is no variation larger than 0.25".
Then we may check how many turns of preload do we get. I think from 1/4 to 1/2 is all we need for 0.030" but I don't trust this method as bolts can stretch.
And another way is to let the engine heats up and check again if the rocker arm is loose or if there is lifter noise.
I also made this table to check what are the odds that we would be out of spec, and I found out that using pushrods with 0.025" length increment, we have 11 out of 26 possible lengths, and if we get 0.011 shorter pushrods, we shift the table to the left and get another 11 possible lengths. And we are left with 0.003 out of the spec if we need 0.022 shorter pushrods, and I assume 0.003 won't be an issue, or Is it enough to cause an issue?
and is it ok to use a different preload on each rocker arm? for example on one side 0.025 preload and on the other 0.035, and would 0.025 preload cause lifter noise?
I haven't found any topic online about using 0.011 as an increment for short travel lifters I see that most people try to be 0.001 accurate and maybe even shim the rocker arm.
do you guys think this is a good compromise for accuracy? and if we are 0.011 off would we go from too short pushrod to too long pushrod and skip zero lash would it be that obvious?
I'll do my best to answer you as I understand the question. The preload window on a 2126 ST is .058". The gain in lash / loss of preload from 70 degrees to operating temperature in an engine is .010". So, if you're perfect, you'd want to get to .038" preload cold, or .028" preload hot.
To address the issue of "There's no way any will be out more than .010", I beg to differ. I almost always end up with one or two bastard lengths on a valve train. I don't know why, but it always seems to happen. It's not an enormous difference. Not like .080 or anything stupid, but I have seen the total range from shortest to longest exceed .030" just from stacked tolerances.
Regarding the accuracy of the pushrods, there are manufacturers who will make custom length pushrods for you in increments of .001". Manton and Manley come to mind. Comp has a new adjustable pushrod system that works via internal shims, and that seems very intriguing as well. However, the threaded adjustable pushrods, there is no "F" in "way" that I would run a motor on the threaded adjustable pushrods. I've had those bend when using them on the standard springs and not the checker springs. in your case, I would definitely take the time to measure all 16, and if you're one of the lucky ones, and you get a number - for example - 7.481 average, and all of them are between 7.476 and 7.487, then Yes, order all 16 at 7.481, and it'll be close enough that you can install them and be fine. The problem with the .050 increments you typically find is at 7.450, you will have many that are too short (loose rockers), and at 7.500, you will have many that are too long (open valves). Your .011" range approach will work as long as the average length pushrod exactly matches the average measured pushrod required. The reason you can get away with it on stock lifters (and most aftermarket hydraulic lifters) is the travel is .170" and higher. Anyway, I'd highly recommend remeasuring all 16 to place the longer ones with the longer measurements and the shorter ones with the shorter measurements.
Now, as to getting resolution better than increments of .025" from the pushrod length checker. Very easy. Ignore the stupid counting rotations method. Get a 8" caliper. Measure your pushrods with the caliper. "But wait", you'll say, "tip to tip is not right, because the cup radius, and the tip is hollow, and gauge length, etc...." And you're correct. But Manton, for example, will work with you on your tip to tip measurements to get your pushrods the exact right length. Just be sure to tell them that's how you measured.
Now, to address preload turns. Very astute on your part. Bolts stretch as they tighten. That's how and why they tighten. When you do your preload checks, do this. Install everything and hand tighten the rocker bolt, but don't tighten it. As delicately as possible, find what I call "dead-soft-touch" with the rocker bolt. There will be some resistance provided by the spring inside the lifter. If you rotate the rocker bolt back and forth, you should be able to find dead soft touch. Now, having found dead soft touch, put your allen wrench on it and note what direction the wrench is facing. NOTE - DO NOT use a ratchet with an allen bit for this part. 20 ft lbs is not hard to achieve. A shorter, hand tool allen wrench is more accurate for this part. Let's for argument sake say you're lucky and it's pointing at 12:00. Now, rotate the bolt until you feel it bottom out, but DO NOT TORQUE THE BOLT. Having done that, the math is very easy. 6:00 is 180 degrees of rotation, and coincidentally, a perfect .038" preload. Anything from 4:00 to 8:00 will be fine, in that it will not bottom out cold at 8:00, and it will not rattle loose hot at 4:00. THEN, tighten to 20-ft lbs. The torque is independent from the preload, and using this method allows you to isolate the preload from the bolt torque.
Now, let's have some more fun. Damn it, one of these is going to 10:00! OK, too long. First make sure you're on the base circle. If not, fix that and try again. Next, try one of your shorter pushrods. If you're still having issues after verifying you're on the base circle and you're using your shortest pushrod, then shim under the pedestal seat with a .010 shim and try again. That .010 shim probably got you into range. You can get a whole shim kit from McMaster Carr pretty cheap.
How about Damn it, one of these is snug at 2:00! No problem. First, find your longest pushrod in the bunch and try again. If that doesn't work, take the pedestal base off and sand it down.
If I did not answer your questions, please let me know. I tried my best to answer them as I interpreted them from your post.
Darth I think has these on his car so he would know how make them work. If you decide to go with this route again go buy the 2116 lifter it has a plunger travel of .093 and can take a preload of .025 to .045 it does about the same thing and you don't need all the different pushrods usually only one or two lengths. I not sure but the 2126 - I thought had like a preload of like .010-.015 maybe??? The problem with these lifters is you really need an adjustable rocker arm or a lot of work and pushrods to get them right. Darth is right there are a lot of variables that go into this - can it be done - yes. And I agree on the adjustable pushrods - no. What I did on mine is I ordered a pushrod from Manton that I knew was too short by like .030 so I had valve lash to measure (like a solid). The reason I do not use and adjustable pushrod (and just measure with a dial caliper) is for consitency I get a 7.86 pushrod from Manton - all my measurements are based on how a Manton pushrod using their measurement and the same ball ends etc. It is just one pushrod so the $20 is fine to get it right. So when I order 16 of the 7.920s I know they are going to be .060 longer than what I did all my measurements off of. I tightened each one down (22 ft pounds) and measured the lash and then back into the preload I need to come up with a length (remember you have a 1.7 or 1.8 rocker ratio when doing this - so .35 on the lash is .20 on the pushrod side). Where you can run into an issue on these exact type situations is that last bit to 22 foot pounds of tq you loose .005-.010 in clearance as the rocker settles into the pedestal with the valve lash method this is taken care of as it is installed and torqued. You can go adjustable rocker arm but you better have more spring for that usually like 40-50 pounds on the nose according to BTR example 400 pounds stock rocker and 450 for adjustable. They also have a footnote on solid steel valve limitations and need for more spring pressure. For what you are doing the 2116 lifter would work fine. I have the 2116 and take it to 7,000 rpm but the titanium intake valves and good valve springs help too.
I'll do my best to answer you as I understand the question. The preload window on a 2126 ST is .058". The gain in lash / loss of preload from 70 degrees to operating temperature in an engine is .010". So, if you're perfect, you'd want to get to .038" preload cold, or .028" preload hot.
To address the issue of "There's no way any will be out more than .010", I beg to differ. I almost always end up with one or two bastard lengths on a valve train. I don't know why, but it always seems to happen. It's not an enormous difference. Not like .080 or anything stupid, but I have seen the total range from shortest to longest exceed .030" just from stacked tolerances.
Regarding the accuracy of the pushrods, there are manufacturers who will make custom length pushrods for you in increments of .001". Manton and Manley come to mind. Comp has a new adjustable pushrod system that works via internal shims, and that seems very intriguing as well. However, the threaded adjustable pushrods, there is no "F" in "way" that I would run a motor on the threaded adjustable pushrods. I've had those bend when using them on the standard springs and not the checker springs. in your case, I would definitely take the time to measure all 16, and if you're one of the lucky ones, and you get a number - for example - 7.481 average, and all of them are between 7.476 and 7.487, then Yes, order all 16 at 7.481, and it'll be close enough that you can install them and be fine. The problem with the .050 increments you typically find is at 7.450, you will have many that are too short (loose rockers), and at 7.500, you will have many that are too long (open valves). Your .011" range approach will work as long as the average length pushrod exactly matches the average measured pushrod required. The reason you can get away with it on stock lifters (and most aftermarket hydraulic lifters) is the travel is .170" and higher. Anyway, I'd highly recommend remeasuring all 16 to place the longer ones with the longer measurements and the shorter ones with the shorter measurements.
Now, as to getting resolution better than increments of .025" from the pushrod length checker. Very easy. Ignore the stupid counting rotations method. Get a 8" caliper. Measure your pushrods with the caliper. "But wait", you'll say, "tip to tip is not right, because the cup radius, and the tip is hollow, and gauge length, etc...." And you're correct. But Manton, for example, will work with you on your tip to tip measurements to get your pushrods the exact right length. Just be sure to tell them that's how you measured.
Now, to address preload turns. Very astute on your part. Bolts stretch as they tighten. That's how and why they tighten. When you do your preload checks, do this. Install everything and hand tighten the rocker bolt, but don't tighten it. As delicately as possible, find what I call "dead-soft-touch" with the rocker bolt. There will be some resistance provided by the spring inside the lifter. If you rotate the rocker bolt back and forth, you should be able to find dead soft touch. Now, having found dead soft touch, put your allen wrench on it and note what direction the wrench is facing. NOTE - DO NOT use a ratchet with an allen bit for this part. 20 ft lbs is not hard to achieve. A shorter, hand tool allen wrench is more accurate for this part. Let's for argument sake say you're lucky and it's pointing at 12:00. Now, rotate the bolt until you feel it bottom out, but DO NOT TORQUE THE BOLT. Having done that, the math is very easy. 6:00 is 180 degrees of rotation, and coincidentally, a perfect .038" preload. Anything from 4:00 to 8:00 will be fine, in that it will not bottom out cold at 8:00, and it will not rattle loose hot at 4:00. THEN, tighten to 20-ft lbs. The torque is independent from the preload, and using this method allows you to isolate the preload from the bolt torque.
Now, let's have some more fun. Damn it, one of these is going to 10:00! OK, too long. First make sure you're on the base circle. If not, fix that and try again. Next, try one of your shorter pushrods. If you're still having issues after verifying you're on the base circle and you're using your shortest pushrod, then shim under the pedestal seat with a .010 shim and try again. That .010 shim probably got you into range. You can get a whole shim kit from McMaster Carr pretty cheap.
How about Damn it, one of these is snug at 2:00! No problem. First, find your longest pushrod in the bunch and try again. If that doesn't work, take the pedestal base off and sand it down.
If I did not answer your questions, please let me know. I tried my best to answer them as I interpreted them from your post.
it did answer my question and I didn't realize that the pedestal seat can be milled down that should make it easier to work with, and just to be sure shimming pedestal decreases preload, milling pedestal increases preload?
do you have a part number for the McMaster carr kit?
and I was wondering how do people get accurate results with checkers and I realized that they are 0.05" per full turn so 1/8 turn 0.00625, I thought it was 0.1" per turn.
we have found a shop that is willing to try and measure the pushrod we will see what happens and then we will decide how to approach this.
is there a reason why you recommend 0.038" preload since it's recommended by johnson lifter to have 0.03" +-0.005" preload, is it to make it quieter? when I called johnson lifter last week he said he likes to have 0.022" free space in the lifter for the oil inside.
Darth I think has these on his car so he would know how make them work. If you decide to go with this route again go buy the 2116 lifter it has a plunger travel of .093 and can take a preload of .025 to .045 it does about the same thing and you don't need all the different pushrods usually only one or two lengths. I not sure but the 2126 - I thought had like a preload of like .010-.015 maybe??? The problem with these lifters is you really need an adjustable rocker arm or a lot of work and pushrods to get them right. Darth is right there are a lot of variables that go into this - can it be done - yes. And I agree on the adjustable pushrods - no. What I did on mine is I ordered a pushrod from Manton that I knew was too short by like .030 so I had valve lash to measure (like a solid). The reason I do not use and adjustable pushrod (and just measure with a dial caliper) is for consitency I get a 7.86 pushrod from Manton - all my measurements are based on how a Manton pushrod using their measurement and the same ball ends etc. It is just one pushrod so the $20 is fine to get it right. So when I order 16 of the 7.920s I know they are going to be .060 longer than what I did all my measurements off of. I tightened each one down (22 ft pounds) and measured the lash and then back into the preload I need to come up with a length (remember you have a 1.7 or 1.8 rocker ratio when doing this - so .35 on the lash is .20 on the pushrod side). Where you can run into an issue on these exact type situations is that last bit to 22 foot pounds of tq you loose .005-.010 in clearance as the rocker settles into the pedestal with the valve lash method this is taken care of as it is installed and torqued. You can go adjustable rocker arm but you better have more spring for that usually like 40-50 pounds on the nose according to BTR example 400 pounds stock rocker and 450 for adjustable. They also have a footnote on solid steel valve limitations and need for more spring pressure. For what you are doing the 2116 lifter would work fine. I have the 2116 and take it to 7,000 rpm but the titanium intake valves and good valve springs help too.
we bought stiffer springs so we can try to run around 8000rpm, we are hoping it would peak around 7400 and carry out the power it 8000rpm, this is the main reason we went with ST2126LSR.
I'm not sure how much of power difference Is between 2116 and ST2126LSR but we wanted to squeeze as much as we can from the engine so we could run constantly low 10's or high 9's.
we never really thought that the local shops would have trouble doing basic measurement if we knew we would have gone with something with bigger margins of error maybe +-0.01"
If you want to get more accurate push rod lengths, look into the EZ chacker Pushrod tool from MS racing compnents. This is the best tool hands down and makes it easy to check them all.
Nice product there. This tool only goes from 7.20 to 7.60 pushrods --- but they have a custom one they can make whatever size for another $40 ($189). On my LS7 with Brodix BR7 heads and the 2116 lifter I have a 7.94 pushrod.
Nice product there. This tool only goes from 7.20 to 7.60 pushrods --- but they have a custom one they can make whatever size for another $40 ($189). On my LS7 with Brodix BR7 heads and the 2116 lifter I have a 7.94 pushrod.
You are correct on that and Yes they can do custom. The owner Mike was very nice to deal with when I ordered mine.
If you want to get more accurate push rod lengths, look into the EZ chacker Pushrod tool from MS racing compnents. This is the best tool hands down and makes it easy to check them all.
It makes measuring pushrods so simple, you’ll be pissed off that you ever tried the other ways. I had mine custom built for longer rods as I knew I’d be in the 8.0 to 8.2 range.
It makes measuring pushrods so simple, you’ll be pissed off that you ever tried the other ways. I had mine custom built for longer rods as I knew I’d be in the 8.0 to 8.2 range.
Curious what application required that length for you? BBC?
Curious what application required that length for you? BBC?
TFS LS7’s
I’ve used the adjustable Comp tools for years. I’ve modded those things every way you can think of to try and make the job easier. Glad I found the MS tool.
TFS LS7’s
I’ve used the adjustable Comp tools for years. I’ve modded those things every way you can think of to try and make the job easier. Glad I found the MS tool.
Oh, I would Like to mention the shim metheod under the stands. I did not cut mine like in the next thread but I did label them for there respective side/ orentation so they dont get mixed up. They are cast and can vary https://ls1tech.com/forums/generatio...cker-arms.html
The size used was 11/32 I.D. x 13x16 O.D. ring shims at McMaster carr. I do not recomend the kit because 1 kit is around $25 and only gives you one of each respective size.
I had to order a few of various sizes and I did get stainles because the price. You can mix and match to get the correct thickness.
I Ordered .001 x QTY:2, .002 X QTY:1, .003 x QTY:1, .005 x QTY:1
You may be able to source them else where cheaper, However I will gladdly pay the convience since they are close by and deliver to my work with a local driver during the day. Same day even if I place in the morning some time before noon.
I think the problem with a BBC is you have the guide plates in the way whereas the LS has no guide plates. The adjuster stop may get in the way. I don't know you might be able to get it in under the guide plates or maybe push a washer under the stud so it simulates a guide plate thickness so you can measure. Plus, the other problem with a BBC is one pushrod is like 8.3 inches and the other is 9.25 inches so you would need to order 2 as there is a 1 inch delta there which not sure how much the tool can have as it appears the range is .400 here but maybe they could do more but the spring thing could be an issue with that much delta.
Yessir. Just about all of the LS7 stuff will end up toward 8” rods, as far as I know, with a common lifter setup.
I had 8.3xx inches on one of my ls7 top ends. There is huge variation in lifter cup heights between manufacturers and even just switching product lines within the same manufacturer.
02-12-2022, 02:31 PM
ST2126LSR Lifter 
