Checking PTV/Lifter Preload/Pushrod Length
Checking PTV/Lifter Preload/Pushrod Length My setup:
2002 LS1
TSP Tsunami camshaft
225 PRC 62cc heads as cast unmilled/MLS head gasket
LS7 lifters
I have searched for days on all of these topics, but at this point I honestly don't know where to start (this is my first build of this magnitude).
Im pretty sure I understand measuring for Pushrod length; Torque rocker arm to 22ft lbs, extend checker tool until play in rocker has been removed (zero lash), count turns on checker to come up with pushrod length (0.05 per turn), and then add in preload for final pushrod length. But what is the proper preload? I know GM calls for 0.05-0.1, but I am reading in my comp cams book 0.02-0.06 preload, and my manager (just so happens to be a ls1 guy) is swearing I need to run 0.03-0.04 preload in order to make more power- he's built a few ls engines in his day, but those numbers seem extremely low to me? Valve float?
PTV, I am not sure which method to use; clay or checker springs. Id prefer to not have to take apart my new heads, considering I have never built a cylinder head before. Also, I realize I will need to use solid lifters if I use clay, but will I need to have my new pushrods handy in order to measure for PTV clearance, or can I use the factory 7.4 rods at zero lash? And can I only check cylinder #1 for clearance, or will I have to check each individual cylinder? I know I SHOULD be alright as far as clearance goes with this setup, but I would rather be safe than sorry.
Thanks in advance, I really appreciate the help.
2002 LS1
TSP Tsunami camshaft
225 PRC 62cc heads as cast unmilled/MLS head gasket
LS7 lifters
I have searched for days on all of these topics, but at this point I honestly don't know where to start (this is my first build of this magnitude).
Im pretty sure I understand measuring for Pushrod length; Torque rocker arm to 22ft lbs, extend checker tool until play in rocker has been removed (zero lash), count turns on checker to come up with pushrod length (0.05 per turn), and then add in preload for final pushrod length. But what is the proper preload? I know GM calls for 0.05-0.1, but I am reading in my comp cams book 0.02-0.06 preload, and my manager (just so happens to be a ls1 guy) is swearing I need to run 0.03-0.04 preload in order to make more power- he's built a few ls engines in his day, but those numbers seem extremely low to me? Valve float?
PTV, I am not sure which method to use; clay or checker springs. Id prefer to not have to take apart my new heads, considering I have never built a cylinder head before. Also, I realize I will need to use solid lifters if I use clay, but will I need to have my new pushrods handy in order to measure for PTV clearance, or can I use the factory 7.4 rods at zero lash? And can I only check cylinder #1 for clearance, or will I have to check each individual cylinder? I know I SHOULD be alright as far as clearance goes with this setup, but I would rather be safe than sorry.
Thanks in advance, I really appreciate the help.
Launching!
Joined: Apr 2015
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I read your post yesterday and passed on it thinking someone else would jump in. It doesn't sound like you have a clear idea of what you're doing. You can't, or at least shouldn't, guess your way through an engine build. Your paragraph about pushrod lengths is either wrong or misstated. Slow down and do some more reading before going further. There is a lot of information available here on your topics, so use it to your advantage. Try asking about one thing at a time and give as much info as you can about your specific parts.
Exactly what I started typing yesterday. I can't help with PTV, but can share this thread with you for measuring pushrods: https://ls1tech.com/forums/generatio...od-length.html
There have been so many pushrod threads lately, it shouldn't be hard to find answers.
There have been so many pushrod threads lately, it shouldn't be hard to find answers.
If you are changing lifters, do you have the old ones? If yes, you can remove the snap ring at the top of one of the old lifters and get some small washers to make a solid lifter.
Check springs are easy to install, but you do need a spring compressor. With performance springs, you will need to change them in the future (if you keep the car) so this might be a good investment now so you can install check springs. Also, with the heads off the car it will be easier to do the first time and understand what is required for later.
I prefer the dial indicator method for check PTV because it provides not only how close but where in the cycle it occurs. However, clay is required to get other clearances to the side of the valve.
One thing you haven't mentioned is adjusting the wipe, you need to do this first so the pushrod length is correct as well as the rocker geometry.
Check springs are easy to install, but you do need a spring compressor. With performance springs, you will need to change them in the future (if you keep the car) so this might be a good investment now so you can install check springs. Also, with the heads off the car it will be easier to do the first time and understand what is required for later.
I prefer the dial indicator method for check PTV because it provides not only how close but where in the cycle it occurs. However, clay is required to get other clearances to the side of the valve.
One thing you haven't mentioned is adjusting the wipe, you need to do this first so the pushrod length is correct as well as the rocker geometry.
I read your post yesterday and passed on it thinking someone else would jump in. It doesn't sound like you have a clear idea of what you're doing. You can't, or at least shouldn't, guess your way through an engine build. Your paragraph about pushrod lengths is either wrong or misstated. Slow down and do some more reading before going further. There is a lot of information available here on your topics, so use it to your advantage. Try asking about one thing at a time and give as much info as you can about your specific parts.
Exactly what I started typing yesterday. I can't help with PTV, but can share this thread with you for measuring pushrods: https://ls1tech.com/forums/generatio...od-length.html
There have been so many pushrod threads lately, it shouldn't be hard to find answers.
There have been so many pushrod threads lately, it shouldn't be hard to find answers.
If you are changing lifters, do you have the old ones? If yes, you can remove the snap ring at the top of one of the old lifters and get some small washers to make a solid lifter.
Check springs are easy to install, but you do need a spring compressor. With performance springs, you will need to change them in the future (if you keep the car) so this might be a good investment now so you can install check springs. Also, with the heads off the car it will be easier to do the first time and understand what is required for later.
I prefer the dial indicator method for check PTV because it provides not only how close but where in the cycle it occurs. However, clay is required to get other clearances to the side of the valve.
One thing you haven't mentioned is adjusting the wipe, you need to do this first so the pushrod length is correct as well as the rocker geometry.
Check springs are easy to install, but you do need a spring compressor. With performance springs, you will need to change them in the future (if you keep the car) so this might be a good investment now so you can install check springs. Also, with the heads off the car it will be easier to do the first time and understand what is required for later.
I prefer the dial indicator method for check PTV because it provides not only how close but where in the cycle it occurs. However, clay is required to get other clearances to the side of the valve.
One thing you haven't mentioned is adjusting the wipe, you need to do this first so the pushrod length is correct as well as the rocker geometry.
It sounds like you suggest using check springs AND clay? As far as the wipe is concerned, it sounds like I have more reading to do. This is all very helpful thank you.
Exactly what I started typing yesterday. I can't help with PTV, but can share this thread with you for measuring pushrods: https://ls1tech.com/forums/generatio...od-length.html
There have been so many pushrod threads lately, it shouldn't be hard to find answers.
There have been so many pushrod threads lately, it shouldn't be hard to find answers.
Yes it's perfectly applicable. For stock rockers you don't need to worry about wipe pattern. Just jump ahead to getting the pushrods.
I highly recommend a 8" digital caliper to measure the pushrods. Much less trouble vs counting rotations, etc.
The method linked should work for almost any rocker configuration except for solid lifters or adjustable rockers. If you have hydraulic lifters and non adjustable rockers - stock or otherwise - method will work. Some preload math is different as rocker ratio changes.
Lastly, don't figure torque into anything when using bolt rotations to gauge preload. When you are preloading the lifter, you are not torquing the bolt. When torquing, you are no longer affecting preload - you're stretching the bolt. Just find zero lash and then add preload.
I highly recommend a 8" digital caliper to measure the pushrods. Much less trouble vs counting rotations, etc.
The method linked should work for almost any rocker configuration except for solid lifters or adjustable rockers. If you have hydraulic lifters and non adjustable rockers - stock or otherwise - method will work. Some preload math is different as rocker ratio changes.
Lastly, don't figure torque into anything when using bolt rotations to gauge preload. When you are preloading the lifter, you are not torquing the bolt. When torquing, you are no longer affecting preload - you're stretching the bolt. Just find zero lash and then add preload.
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Also to go back and answer some other questions:
1. The preload largely depends on which lifters you run. I run short travels with only .058" total movement and I preloaded to 038". I did each one individually measured and verified. All are between .031 and .045. For morels, 050 is what ice read. For LS7 lifters, 070. Total ls7 travel is 170. The real secret is to take the time to get them preloaded close to the same so each cylinder is basics the same which is how the motor makes the most power
2. PTV can just to cylinder 1 and be fine.
3. With LS7 lifters you could just measure cylinder 1 and the motor will run fine. There is power left on the table versus measuring all of them and optimizing lengths for consistent preload.
Hope all that helps
1. The preload largely depends on which lifters you run. I run short travels with only .058" total movement and I preloaded to 038". I did each one individually measured and verified. All are between .031 and .045. For morels, 050 is what ice read. For LS7 lifters, 070. Total ls7 travel is 170. The real secret is to take the time to get them preloaded close to the same so each cylinder is basics the same which is how the motor makes the most power
2. PTV can just to cylinder 1 and be fine.
3. With LS7 lifters you could just measure cylinder 1 and the motor will run fine. There is power left on the table versus measuring all of them and optimizing lengths for consistent preload.
Hope all that helps
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Brett Foote Yes it's perfectly applicable. For stock rockers you don't need to worry about wipe pattern. Just jump ahead to getting the pushrods.
I highly recommend a 8" digital caliper to measure the pushrods. Much less trouble vs counting rotations, etc.
The method linked should work for almost any rocker configuration except for solid lifters or adjustable rockers. If you have hydraulic lifters and non adjustable rockers - stock or otherwise - method will work. Some preload math is different as rocker ratio changes.
Lastly, don't figure torque into anything when using bolt rotations to gauge preload. When you are preloading the lifter, you are not torquing the bolt. When torquing, you are no longer affecting preload - you're stretching the bolt. Just find zero lash and then add preload.
I highly recommend a 8" digital caliper to measure the pushrods. Much less trouble vs counting rotations, etc.
The method linked should work for almost any rocker configuration except for solid lifters or adjustable rockers. If you have hydraulic lifters and non adjustable rockers - stock or otherwise - method will work. Some preload math is different as rocker ratio changes.
Lastly, don't figure torque into anything when using bolt rotations to gauge preload. When you are preloading the lifter, you are not torquing the bolt. When torquing, you are no longer affecting preload - you're stretching the bolt. Just find zero lash and then add preload.
Also to go back and answer some other questions:
1. The preload largely depends on which lifters you run. I run short travels with only .058" total movement and I preloaded to 038". I did each one individually measured and verified. All are between .031 and .045. For morels, 050 is what ice read. For LS7 lifters, 070. Total ls7 travel is 170. The real secret is to take the time to get them preloaded close to the same so each cylinder is basics the same which is how the motor makes the most power
2. PTV can just to cylinder 1 and be fine.
3. With LS7 lifters you could just measure cylinder 1 and the motor will run fine. There is power left on the table versus measuring all of them and optimizing lengths for consistent preload.
Hope all that helps
1. The preload largely depends on which lifters you run. I run short travels with only .058" total movement and I preloaded to 038". I did each one individually measured and verified. All are between .031 and .045. For morels, 050 is what ice read. For LS7 lifters, 070. Total ls7 travel is 170. The real secret is to take the time to get them preloaded close to the same so each cylinder is basics the same which is how the motor makes the most power
2. PTV can just to cylinder 1 and be fine.
3. With LS7 lifters you could just measure cylinder 1 and the motor will run fine. There is power left on the table versus measuring all of them and optimizing lengths for consistent preload.
Hope all that helps
happy to help! Like Brew said. Take your time. After a few tries you'll be able to repeat your measurements and you'll know you have it. Take a few times just practicing technique. It'll sort of just click into place and then you'll be cranking right through it. Best of luck
So I got a solid day in the garage and managed to get the lifters in and measure for pushrod length on all 4 corner cylinders. Lifters were not soaked prior to install.
My measurements came in at (before adding in preload):
Cylinder 1
Intake: 7.4375
Exhaust: 7.425
Cylinder 7
Intake: 7.4375
Exhaust:7.425
Cylinderer 2
Intake: 7.4375
Exhaust: 7.4125
Cylinder 8
Intake: 7.45
Exhaust: 7.425
At this point I am just debating what preload to run with.
My measurements came in at (before adding in preload):
Cylinder 1
Intake: 7.4375
Exhaust: 7.425
Cylinder 7
Intake: 7.4375
Exhaust:7.425
Cylinderer 2
Intake: 7.4375
Exhaust: 7.4125
Cylinder 8
Intake: 7.45
Exhaust: 7.425
At this point I am just debating what preload to run with.
Ok. The numbers you got look pretty good. It's not unusual to get one or two rogue pushrod lengths especially with stock rockers. There are two ways you could look at it
1. Average your highest and lowest PR and you get 7.432.
2. Throw those two out and average everything else and you get 7.431.
A little higher than I'd expect for zero lash, but if that's what you got and its repeatable that's what matters.
Add ~070 for LS7, puts you right in the middle of the preload range at 7.500".
If you order 7.500, they'll measure out to 7.515-7.520. So you'll probably want a custom set at 7.485. When they come in, measure them all. Put the longest ones and the shortest ones where appropriate.
Best of luck!
1. Average your highest and lowest PR and you get 7.432.
2. Throw those two out and average everything else and you get 7.431.
A little higher than I'd expect for zero lash, but if that's what you got and its repeatable that's what matters.
Add ~070 for LS7, puts you right in the middle of the preload range at 7.500".
If you order 7.500, they'll measure out to 7.515-7.520. So you'll probably want a custom set at 7.485. When they come in, measure them all. Put the longest ones and the shortest ones where appropriate.
Best of luck!
Ok. The numbers you got look pretty good. It's not unusual to get one or two rogue pushrod lengths especially with stock rockers. There are two ways you could look at it
1. Average your highest and lowest PR and you get 7.432.
2. Throw those two out and average everything else and you get 7.431.
A little higher than I'd expect for zero lash, but if that's what you got and its repeatable that's what matters.
Add ~070 for LS7, puts you right in the middle of the preload range at 7.500".
If you order 7.500, they'll measure out to 7.515-7.520. So you'll probably want a custom set at 7.485. When they come in, measure them all. Put the longest ones and the shortest ones where appropriate.
Best of luck!
1. Average your highest and lowest PR and you get 7.432.
2. Throw those two out and average everything else and you get 7.431.
A little higher than I'd expect for zero lash, but if that's what you got and its repeatable that's what matters.
Add ~070 for LS7, puts you right in the middle of the preload range at 7.500".
If you order 7.500, they'll measure out to 7.515-7.520. So you'll probably want a custom set at 7.485. When they come in, measure them all. Put the longest ones and the shortest ones where appropriate.
Best of luck!
using quarter turns. Most of the intake valve rockers were too loose/had vertical play at 12.5 turns, and felt fairly tight at 12.75 turns of the checker. In this scenario, I went with 12.75 turns. The best i can figure is the geometry on the TSP heads is different from gm castings and calls for a longer rod?
I was not aware that pushrods ran long; again, thats really helpful thank you.
They might. It would definitely be worth asking. Aftermarket heads do sometimes run taller.
My previous rods were 7.7" long!
I don't trust the counting rotations method much. If you can borrow a caliper or buy one and directly measure, that is best
My previous rods were 7.7" long!
I don't trust the counting rotations method much. If you can borrow a caliper or buy one and directly measure, that is best
Hey guys, I just wanted to give an update. I built this motor for a LSX/RX-7 swap, and I currently have the motor and trans in the car, accessories installed, and have begun running the harness. Im buying and installing random sensors, goodies, etc in an effort to wrap everything up. Im hoping to test start this thing in the next week. Ill keep you posted; hopefully it doesn't grenade on me!!
I am going to need to read through this thread real carefully soon.. this is the part of the job that confuses me the most and cant seem to get a grasp on it.. hopefully reading some of this over as im doing it will make more sense..i would have never expected it would be so tedious and complicated