[Z06] Push Rod/ Lifter preload
02-27-2017, 07:09 PM
#21
Melting Slicks
I don't see how you can get the zero lash and added preload method wrong. But anything is possible given human error. As I stated the counting turns method worked for me as well within .004 using the numbers I found on the forum. So either way you CAN figure it out. Like outhouse said try both to confirm and go from there.
Omega, I , like you feel as if the bolt turn method with these engines is a little inaccurate. It no doubt works and even my results were close to measuring using the same zero lash method as you, but I feel more comfortable with it than counting turns. Now if I had a polylock my opinion may differ lol. But are you saying you ordered 10 different length pushrods for one engine?
Correct 10 different lengths.
These were my measurements to zero lash. With a .030" spec you can see why this was necessary. They are long because of the Johnson ST2126 lifter I am running.
Last edited by User Omega; 02-27-2017 at 07:09 PM.
02-27-2017, 09:36 PM
#23
Safety Car
No kidding.
When I did mine I researched this and those were they guys who seemed to always have problems.
For mine I tightened the BTR rods and I ended up with 2 1/4 ish turns, and changed one size and was right in the golden zone.
What was cool was AHP sent them out with a quick phone call before they received my return.
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American Heritage (02-28-2017)
02-27-2017, 09:54 PM
#24
Melting Slicks
No kidding.
When I did mine I researched this and those were they guys who seemed to always have problems.
For mine I tightened the BTR rods and I ended up with 2 1/4 ish turns, and changed one size and was right in the golden zone.
What was cool was AHP sent them out with a quick phone call before they received my return.
When I did mine I researched this and those were they guys who seemed to always have problems.
For mine I tightened the BTR rods and I ended up with 2 1/4 ish turns, and changed one size and was right in the golden zone.
What was cool was AHP sent them out with a quick phone call before they received my return.
AHP is a great company no dount. I owed Mamo the business because he was willing to give me direction with this and my intake. He has always been fair with me. Those guys are the only two that haven't jacked me around through this build when I needed something.
02-28-2017, 02:00 AM
#25
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As Outhouse mentioned we like to see between 1 1/2 - 1 3/4 turns on on the rocker bolt from zero lash to 22 ft/lbs with the GM LS7 lifters.
As a general "per-flight check" to make sure your within a broad range counting turns on the rocker bolt works very well. The only real possibility of error on this method is doing it when the camshaft lobe for the rocker your checking is not on base circle or misjudging the zero lash point.
If your running aftermarket lifters such as Johnson, Morel or Comp you will want to follow the recommended preload for that lifer. Surprisingly most the aftermarket lifters dont come with any literature telling you the preload they recommend so often times you will have to call tech support or look on their website (if they have the data on their site that is).
As a general "per-flight check" to make sure your within a broad range counting turns on the rocker bolt works very well. The only real possibility of error on this method is doing it when the camshaft lobe for the rocker your checking is not on base circle or misjudging the zero lash point.
If your running aftermarket lifters such as Johnson, Morel or Comp you will want to follow the recommended preload for that lifer. Surprisingly most the aftermarket lifters dont come with any literature telling you the preload they recommend so often times you will have to call tech support or look on their website (if they have the data on their site that is).
02-28-2017, 10:57 PM
#26
Ok so I guess I'm just looking at this too elementary , you have 7.80 length pushrods from the factory , you have factory lifters , you have factory rockers and hardware , you have factory head gaskets , your car is running fine with normal zo6 valvetrain noise . You pull your heads and have them milled .040 . You reinstall using the exact same factory parts including head gaskets . Tell me why you can't buy a pushrod that's .040 shorter and be perfectly fine assuming your heads were milled flat and not angle milled ? I understand the logic in all the perfectionists on here but I can't see with a stock hydraulic lifter with a wide tolerance for preload that can still function normally under these conditions why there is so much rigamoro to choosing a push rod length .
Last edited by injfuel; 02-28-2017 at 10:58 PM.
03-01-2017, 02:52 PM
#27
Bolt pitch: 1.25mm (0.0492") per 360deg.
Rocker ratio: 1.8 (LS7)
2.8 (rocker length)/1.8 (rocker ratio) = 1.556
1 rotation of bolt = 0.0492" x 1.556 ratio = 0.0765" preload at the lifter.
Done.
Rocker ratio: 1.8 (LS7)
2.8 (rocker length)/1.8 (rocker ratio) = 1.556
1 rotation of bolt = 0.0492" x 1.556 ratio = 0.0765" preload at the lifter.
Done.
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Nowanker (04-21-2017)
03-01-2017, 04:13 PM
#28
Melting Slicks
Ok so I guess I'm just looking at this too elementary , you have 7.80 length pushrods from the factory , you have factory lifters , you have factory rockers and hardware , you have factory head gaskets , your car is running fine with normal zo6 valvetrain noise . You pull your heads and have them milled .040 . You reinstall using the exact same factory parts including head gaskets . Tell me why you can't buy a pushrod that's .040 shorter and be perfectly fine assuming your heads were milled flat and not angle milled ? I understand the logic in all the perfectionists on here but I can't see with a stock hydraulic lifter with a wide tolerance for preload that can still function normally under these conditions why there is so much rigamoro to choosing a push rod length .
My valve train is fairly quiet, although I can hear it. I am sure if I measured and ordered custom push rods for every valve, it would quiet down some. If I ever pull my heads again I might go for a higher quality lifter than the GM LS7 lifter and do new push rods that are all custom length.
03-01-2017, 07:52 PM
#30
Safety Car
03-01-2017, 08:45 PM
#31
Yea I just read that as I researched more , I just picked up the comp cams pushrod length checker from BTR , I feel I have all the correct info to check my length now . Also got some digital calipers that go to 8 inches to check length as through my research I don't trust counting the turns on the adjustable pushrod .
03-01-2017, 09:48 PM
#32
Melting Slicks
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I measured the lifter travel at the rocker with a dial indicator to come up with my .160" travel, and my calculated "1 turn of the bolt equals .084" (LS1 rocker) matched up pretty well with my measurement of .078".
But just to further complicate things, there a different ways to measure pushrod length...
I checked some Comp P-rods that I had on the shelf, and they measured .020" longer than was marked on them.
But just to further complicate things, there a different ways to measure pushrod length...
I checked some Comp P-rods that I had on the shelf, and they measured .020" longer than was marked on them.
03-02-2017, 09:25 PM
#34
03-02-2017, 09:48 PM
#35
Melting Slicks
The lifter has more than adequate spring pressure to hold the plunger up. You drop the new lifters in and measure them installed.
03-03-2017, 07:57 AM
#36
Let me recap from my research to double verify because people make it very complicated , also keep in mind I'll be using a set of digital micrometers instead of counting the turns on the adjustable pushrod , you have your adjustable pushrod installed , your rocker needs to be seated firmly against the pedestal but NOT torqued (some bolt down but don't torque , some say you can firmly hold it down against the pedestal with your hand ) you then check for up and down play (which you want NONE of that) . Once you've reached a point where you've adjusted your pushrod to eliminated all up and down play you want to be sure you have just a touch of side to side play to verify it's not pushing the plunger down . Then pull your adjustable pushrod out , measure it's length and add .075 for pre load on the stock Ls7 lifters and then go order them . Does this sound accurate ?
03-03-2017, 01:07 PM
#37
Safety Car
Yes @injfuel, as long as the lifter is on the base circle of the camshaft.
If you have any concerns about what you're ordering, use the "count turns" method to _verify_ your math is correct. When your pushrod adjusted for 0 lash, add .075 to it, tape it up really well and install it. As you tighten the rocker, stop at 0 lash, and use your torque wrench to final torque to 22 ft lbs while paying attention to how many degrees it takes. This is _not_ a substitute for measuring, but it's a good way to double check you haven't done something wrong in your math or measuring.
If you have any concerns about what you're ordering, use the "count turns" method to _verify_ your math is correct. When your pushrod adjusted for 0 lash, add .075 to it, tape it up really well and install it. As you tighten the rocker, stop at 0 lash, and use your torque wrench to final torque to 22 ft lbs while paying attention to how many degrees it takes. This is _not_ a substitute for measuring, but it's a good way to double check you haven't done something wrong in your math or measuring.
03-03-2017, 02:27 PM
#38
For the record, measuring with a pushrod checker I had a theoretical preload of .080 of with the pushrods I ordered. Installed them, from zero lash to torqued was 1.125 turn or there abouts. Motor is far quieter than stock which made me happy.
03-03-2017, 06:26 PM
#39
Yes @injfuel, as long as the lifter is on the base circle of the camshaft.
If you have any concerns about what you're ordering, use the "count turns" method to _verify_ your math is correct. When your pushrod adjusted for 0 lash, add .075 to it, tape it up really well and install it. As you tighten the rocker, stop at 0 lash, and use your torque wrench to final torque to 22 ft lbs while paying attention to how many degrees it takes. This is _not_ a substitute for measuring, but it's a good way to double check you haven't done something wrong in your math or measuring.
If you have any concerns about what you're ordering, use the "count turns" method to _verify_ your math is correct. When your pushrod adjusted for 0 lash, add .075 to it, tape it up really well and install it. As you tighten the rocker, stop at 0 lash, and use your torque wrench to final torque to 22 ft lbs while paying attention to how many degrees it takes. This is _not_ a substitute for measuring, but it's a good way to double check you haven't done something wrong in your math or measuring.
03-03-2017, 06:27 PM
#40
I have a decent size lift cam so I need this to be right , I hope mine works out to be as quiet as yours !!