inconsistent lifter preload...advice needed
Thread Starter
Staging Lane
Joined: May 2019
Posts: 73
Likes: 6
From: Northern VA
Pushrod checkers...sure I did that. I don't have that big of calipers yet, I count turns, gave me 7.343 ~ 7.356. Then added 0.040+/-0.010. So 7.400" sounds about right. But this is not the end of story, as once I got 7.4 PRs in there, the 8 rockers on one side (installed one head) asking for 0.087 ~ 0.120" after zero lash to torqued to 22 measured by a dial indicator. Now I'm thinking, I need at least 2 of 7.300, few 7.325s and 7.350s to correct this and bring all to that 0.040" range of preload. That's crazy.
Thread Starter
Staging Lane
Joined: May 2019
Posts: 73
Likes: 6
From: Northern VA
So I got 3 different length to bring them in 0.040+/-0.010 range. mostly 7.325, few 7.350, two 7.300. Now, I have few of them shorter 7.325 gives 0.028" preload, 7.350 gives 0.053. And no, I'm not gonna call Manton for custom $$$$$ PRs. Will just get shelf PRs from BTR. Which side you go. Lower preload or higher? When gets hot, preload increases or decreases?
Thread Starter
Staging Lane
Joined: May 2019
Posts: 73
Likes: 6
From: Northern VA
The rocker arms are fixed onto the pedestal rail therefore the swipe can only change by either raising or lowering the rocker arm or changing the height of the valve stem. Have you ever layed the straight edge across the tops of the valves to see if they were all the same height?
Thread Starter
Staging Lane
Joined: May 2019
Posts: 73
Likes: 6
From: Northern VA
The rocker arms are fixed onto the pedestal rail therefore the swipe can only change by either raising or lowering the rocker arm or changing the height of the valve stem. Have you ever layed the straight edge across the tops of the valves to see if they were all the same height?
. Exhaust Valve #4 yield 0.043" preload with 7.300" pushrod (in range) Exhaust Valve #6 yield 0.030" preload with 7.300" PR and 0.055 with 7.325" PR ( 0.030" is minimum preload per Johnson for these 3110Rs). Intake #6 : 0.028 preload w/ 7.350 and 0.053 w /7.375 PR. 7.300 PRs are on back order and I need to wait, no problem, I wait...but don't know what to do with those which 0.025" increment won't bring them in range. Only one head is installed. trying to figure out PRs so I can check my PTV clearance and degree it on the other side. Heads done by TSP. 
Can't believe TSP would send out heads with inconsistent valve heights. I've seen intake valves on LS3 heads being about 0.025 higher than the exhaust valves due to the stem height being slightly higher on the LS3 hollow stem valves but most of the time the tops of the valves are all even and when you lay a straight edge across the top it makes contact with all of the valves. They could get away with this on stock lifters due to the wider range of lifter preload.
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Launching!
Joined: Oct 2022
Posts: 206
Likes: 74
From: FL
If any lesson was to be learned here it would be to check others work before assembly.
If someone bought a $12,000 crate engine and found shims under lifters, pedestals machined five different heights, three different sized pushrods (yes I do understand not all of this has been done here) they'd probably be disappointed. Might even think about how poorly done the set up was.
I guess I'm lucky to have a family owned machine shop nearby who could correct the underlying problems easily. It's never too late to pull the heads back off and make it so the final assembly will be right.
If someone bought a $12,000 crate engine and found shims under lifters, pedestals machined five different heights, three different sized pushrods (yes I do understand not all of this has been done here) they'd probably be disappointed. Might even think about how poorly done the set up was.
I guess I'm lucky to have a family owned machine shop nearby who could correct the underlying problems easily. It's never too late to pull the heads back off and make it so the final assembly will be right.
Length of pushrod checker should be measured with a caliper. Do not trust the "turns of thread" method, I have 4 of the same Comp Cams checker tools and they are all different length. You can get away with that kind of slop with stock lifters because of the wide tolerance of preload, but you don't want to rely on counting turns with Johnson low-travel lifters. I wrap teflon tape on the threads of the checker tool so it doesn't move on me while handling.
After you get the zero lash lengths with checker tool for every rocker, you'll have to make adjustments for final length of pushrod. Add length for lifter preload, account for expansion of block when hot, and also a correction for the diameter of the ball end of the checker tool vs. the actual pushrod. Places like Manton can do all these adjustments for you. And they'll organize your numbers into groupings to decide how many different lengths they will send you. Manton pushrods have a 0.003- 0.008" tolerance as manufactured and will grow or shrink by 0.015" with a 25F temp swing. Manton has a lot of experience with Johnson lifters and is the primary supplier of pushrods because they are so accurate with lengths. The cost of Manton pushrods is not a lot more than off-the-shelf stuff, it's foolish to not buy Manton when you spent $900 on lifters.
When you get your new pushrods they will not appear to be exactly the length you ordered. The pushrods are manufactured and length checked at 70F and the length will change at different temperatures. Don't freak out about it, just verify all the lengths in each grouping are reasonably correct and similar before installing in your engine.
You can verify lifter preload during assembly using a micrometer or by angle of turn of rocker bolt from zero lash to where the rocker seats on the pedestal. Turns after seating don't matter, that's just stretching bolt threads to reach final torque.
The point of all this attention to detail is to aim small so you miss small. The lifters don't actually need that much accuracy. Main goal is to not overload the lifter. A 0.025" preload when hot is perfect (corresponds to 0.040 cold). A window of 0.038 - 0.045" preload during assembly is a good range. The more the plunger is pushed in (preloaded) the less vacuum the engine will produce. Johnson is being really conservative about the preload tolerance because they don't want to overload the lifters, they used to advertise wider specs with the same product.
After you get the zero lash lengths with checker tool for every rocker, you'll have to make adjustments for final length of pushrod. Add length for lifter preload, account for expansion of block when hot, and also a correction for the diameter of the ball end of the checker tool vs. the actual pushrod. Places like Manton can do all these adjustments for you. And they'll organize your numbers into groupings to decide how many different lengths they will send you. Manton pushrods have a 0.003- 0.008" tolerance as manufactured and will grow or shrink by 0.015" with a 25F temp swing. Manton has a lot of experience with Johnson lifters and is the primary supplier of pushrods because they are so accurate with lengths. The cost of Manton pushrods is not a lot more than off-the-shelf stuff, it's foolish to not buy Manton when you spent $900 on lifters.
When you get your new pushrods they will not appear to be exactly the length you ordered. The pushrods are manufactured and length checked at 70F and the length will change at different temperatures. Don't freak out about it, just verify all the lengths in each grouping are reasonably correct and similar before installing in your engine.
You can verify lifter preload during assembly using a micrometer or by angle of turn of rocker bolt from zero lash to where the rocker seats on the pedestal. Turns after seating don't matter, that's just stretching bolt threads to reach final torque.
The point of all this attention to detail is to aim small so you miss small. The lifters don't actually need that much accuracy. Main goal is to not overload the lifter. A 0.025" preload when hot is perfect (corresponds to 0.040 cold). A window of 0.038 - 0.045" preload during assembly is a good range. The more the plunger is pushed in (preloaded) the less vacuum the engine will produce. Johnson is being really conservative about the preload tolerance because they don't want to overload the lifters, they used to advertise wider specs with the same product.
Thread Starter
Staging Lane
Joined: May 2019
Posts: 73
Likes: 6
From: Northern VA
Length of pushrod checker should be measured with a caliper. Do not trust the "turns of thread" method, I have 4 of the same Comp Cams checker tools and they are all different length. You can get away with that kind of slop with stock lifters because of the wide tolerance of preload, but you don't want to rely on counting turns with Johnson low-travel lifters. I wrap teflon tape on the threads of the checker tool so it doesn't move on me while handling.
After you get the zero lash lengths with checker tool for every rocker, you'll have to make adjustments for final length of pushrod. Add length for lifter preload, account for expansion of block when hot, and also a correction for the diameter of the ball end of the checker tool vs. the actual pushrod. Places like Manton can do all these adjustments for you. And they'll organize your numbers into groupings to decide how many different lengths they will send you. Manton pushrods have a 0.003- 0.008" tolerance as manufactured and will grow or shrink by 0.015" with a 25F temp swing. Manton has a lot of experience with Johnson lifters and is the primary supplier of pushrods because they are so accurate with lengths. The cost of Manton pushrods is not a lot more than off-the-shelf stuff, it's foolish to not buy Manton when you spent $900 on lifters.
When you get your new pushrods they will not appear to be exactly the length you ordered. The pushrods are manufactured and length checked at 70F and the length will change at different temperatures. Don't freak out about it, just verify all the lengths in each grouping are reasonably correct and similar before installing in your engine.
You can verify lifter preload during assembly using a micrometer or by angle of turn of rocker bolt from zero lash to where the rocker seats on the pedestal. Turns after seating don't matter, that's just stretching bolt threads to reach final torque.
The point of all this attention to detail is to aim small so you miss small. The lifters don't actually need that much accuracy. Main goal is to not overload the lifter. A 0.025" preload when hot is perfect (corresponds to 0.040 cold). A window of 0.038 - 0.045" preload during assembly is a good range. The more the plunger is pushed in (preloaded) the less vacuum the engine will produce. Johnson is being really conservative about the preload tolerance because they don't want to overload the lifters, they used to advertise wider specs with the same product.
After you get the zero lash lengths with checker tool for every rocker, you'll have to make adjustments for final length of pushrod. Add length for lifter preload, account for expansion of block when hot, and also a correction for the diameter of the ball end of the checker tool vs. the actual pushrod. Places like Manton can do all these adjustments for you. And they'll organize your numbers into groupings to decide how many different lengths they will send you. Manton pushrods have a 0.003- 0.008" tolerance as manufactured and will grow or shrink by 0.015" with a 25F temp swing. Manton has a lot of experience with Johnson lifters and is the primary supplier of pushrods because they are so accurate with lengths. The cost of Manton pushrods is not a lot more than off-the-shelf stuff, it's foolish to not buy Manton when you spent $900 on lifters.
When you get your new pushrods they will not appear to be exactly the length you ordered. The pushrods are manufactured and length checked at 70F and the length will change at different temperatures. Don't freak out about it, just verify all the lengths in each grouping are reasonably correct and similar before installing in your engine.
You can verify lifter preload during assembly using a micrometer or by angle of turn of rocker bolt from zero lash to where the rocker seats on the pedestal. Turns after seating don't matter, that's just stretching bolt threads to reach final torque.
The point of all this attention to detail is to aim small so you miss small. The lifters don't actually need that much accuracy. Main goal is to not overload the lifter. A 0.025" preload when hot is perfect (corresponds to 0.040 cold). A window of 0.038 - 0.045" preload during assembly is a good range. The more the plunger is pushed in (preloaded) the less vacuum the engine will produce. Johnson is being really conservative about the preload tolerance because they don't want to overload the lifters, they used to advertise wider specs with the same product.
Now...I talked with TSP and explained what's going on. They said, If is the machine work defect, we fix it, but since we reused your valves, if inconsistency caused by valves, you'll need to buy new valves.
I need some help figure if these variation is normal and I can proceed with custom length PR, or essentially using multiple size PRs in one engine considered normal, or else I have to send them back to be reworked. To my understanding, "installed valve heights" are not even, I checked with straight edge. Even then I still not sure once I receive them back how many different length PR I'd need, or all will be using one or 2 sizes. If someone can help with that.
I agree with the above.
Using a dial indicator is good. You can loosen the rocker bolt and with slight finger presser zero the gauge, tighten the bolt , note the preload and back off the bolt to double check the preload. If the lifter is "pumped up" just be patience as the spring will bleed the lifter down for the reading. If the push rod is too long, you can put a shim under the rocker arm support if it is not too much, the aluminum will flex. Also I have removed material from the supports if the Push Rods are too short.
Hope that helps
Using a dial indicator is good. You can loosen the rocker bolt and with slight finger presser zero the gauge, tighten the bolt , note the preload and back off the bolt to double check the preload. If the lifter is "pumped up" just be patience as the spring will bleed the lifter down for the reading. If the push rod is too long, you can put a shim under the rocker arm support if it is not too much, the aluminum will flex. Also I have removed material from the supports if the Push Rods are too short.
Hope that helps
I've had off of the shelf push rods as well as custom length push rods be off by as much as .015"-.020".
Bad valve jobs can make the process a pita too. Fortunately I have a decent set of Mitutoyo calipers to measure the push rods.
Bad valve jobs can make the process a pita too. Fortunately I have a decent set of Mitutoyo calipers to measure the push rods.
Launching!
Joined: Feb 2018
Posts: 223
Likes: 31
From: Bismarck, ND
Poor putty cat The OP was using a dial indicator to check the preload and was getting inconsistent readings. So that is why I mentioned to wait for the bleed down.
I have used both methods, the PR and dial indicator. With a dial, finding zero preload is very easy.
On a side note for the OP: I would check that by adding shims between the rocker and the support that the contact area does not happen just on the high part of the supports.
On a half circle. .010" on the bottom would add .020" on the sides. The supports are not a full half circle [180 degrees] but you see what I mean.
Hope that helps
Thread Starter
Staging Lane
Joined: May 2019
Posts: 73
Likes: 6
From: Northern VA
Yup, it is just another way to skin a cat.
The OP was using a dial indicator to check the preload and was getting inconsistent readings. So that is why I mentioned to wait for the bleed down.
I have used both methods, the PR and dial indicator. With a dial, finding zero preload is very easy.
On a side note for the OP: I would check that by adding shims between the rocker and the support that the contact area does not happen just on the high part of the supports.
On a half circle. .010" on the bottom would add .020" on the sides. The supports are not a full half circle [180 degrees] but you see what I mean.
Hope that helps
The OP was using a dial indicator to check the preload and was getting inconsistent readings. So that is why I mentioned to wait for the bleed down.
I have used both methods, the PR and dial indicator. With a dial, finding zero preload is very easy.
On a side note for the OP: I would check that by adding shims between the rocker and the support that the contact area does not happen just on the high part of the supports.
On a half circle. .010" on the bottom would add .020" on the sides. The supports are not a full half circle [180 degrees] but you see what I mean.
Hope that helps
I talked with manton and he said yes, you can get custom prs and go, but range of what your prs want to be are just too wide. I just gonna send them back to tsp to be corrected.