Is this the correct way to calculate lifter preload?
08-27-2008, 02:41 PM
#1
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Is this the correct way to calculate lifter preload? I have used the information ive found to calculate my lifter preload but to be sure ima use a pushrod length checker after I get it all together. Here is what I have calculated it as being.
7.380 Stock Pushrod
0.025 LS6 Cam Base Circle Diff (.050" Total)
-0.060 LS7 Lifter cup is .060 shallower (FIXED)
7.345 My Pushrod Size
0.080 Plus Preload
7.425 Total Pushrod Length
Isnt adding the preload to the pushrod size correct?
7.380 Stock Pushrod
0.025 LS6 Cam Base Circle Diff (.050" Total)
-0.060 LS7 Lifter cup is .060 shallower (FIXED)
7.345 My Pushrod Size
0.080 Plus Preload
7.425 Total Pushrod Length
Isnt adding the preload to the pushrod size correct?
Last edited by Mike96z; 08-27-2008 at 08:12 PM.
08-27-2008, 03:48 PM
#3
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Stock rockers. The LS7 lifter isnt actually longer (my bad) but the cup depth is .060 shallower so that adds into the equation. Im no lnnger gonna mill.
08-27-2008, 07:38 PM
#6
You better recheck all of your measurements.
The stock pushrods are 7.400"
Base circle of aftermarket cams is usually .050" smaller
LS7 and LS1,LS2,LS3 etc lifters are all the same service part number
Assemble all of the part or at least one pushrod and rocker on each side and buy a pushrod checker and get the correct distance.
Odds are you won't need anything but stock length pushrods.
The stock pushrods are 7.400"
Base circle of aftermarket cams is usually .050" smaller
LS7 and LS1,LS2,LS3 etc lifters are all the same service part number
Assemble all of the part or at least one pushrod and rocker on each side and buy a pushrod checker and get the correct distance.
Odds are you won't need anything but stock length pushrods.
08-27-2008, 07:47 PM
#7
Not sure how you measured the lifter, but it might be worth a double check.
If you have an adjustable pushrod, take it apart and use the short end. Put the round end of the short half of the adjustable pushrod in the lifter cup and then measure from the roller to the top of the adjustable pushrod half where the threads are. Do this with both the stock and the LS7. I thought they were the same and would be surprised if they are not.
If you have an adjustable pushrod, take it apart and use the short end. Put the round end of the short half of the adjustable pushrod in the lifter cup and then measure from the roller to the top of the adjustable pushrod half where the threads are. Do this with both the stock and the LS7. I thought they were the same and would be surprised if they are not.
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08-27-2008, 08:09 PM
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Not sure how you measured the lifter, but it might be worth a double check.
If you have an adjustable pushrod, take it apart and use the short end. Put the round end of the short half of the adjustable pushrod in the lifter cup and then measure from the roller to the top of the adjustable pushrod half where the threads are. Do this with both the stock and the LS7. I thought they were the same and would be surprised if they are not.
If you have an adjustable pushrod, take it apart and use the short end. Put the round end of the short half of the adjustable pushrod in the lifter cup and then measure from the roller to the top of the adjustable pushrod half where the threads are. Do this with both the stock and the LS7. I thought they were the same and would be surprised if they are not.
The LS6 cam is a .050" diff so /2 = .025" on each side (19mm base circle)
Stock pushrods are 7.380, I thought they were 7.400" also but I was proven otherwise from GM.
08-27-2008, 08:37 PM
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I agree with using the pushrod checker on engine, it's the best way rather relying on supposably accurate dimensions. Each engine is a little different and the tolerances may add up combinations that make calculations come up short.
08-27-2008, 08:56 PM
#10
I have used the information ive found to calculate my lifter preload but to be sure ima use a pushrod length checker after I get it all together. Here is what I have calculated it as being.
7.380 Stock Pushrod
0.025 LS6 Cam Base Circle Diff (.050" Total)
-0.060 LS7 Lifter cup is .060 shallower (FIXED)
7.345 My Pushrod Size
0.080 Plus Preload
7.425 Total Pushrod Length
Isnt adding the preload to the pushrod size correct?
7.380 Stock Pushrod
0.025 LS6 Cam Base Circle Diff (.050" Total)
-0.060 LS7 Lifter cup is .060 shallower (FIXED)
7.345 My Pushrod Size
0.080 Plus Preload
7.425 Total Pushrod Length
Isnt adding the preload to the pushrod size correct?
By taking the factory measurments and figuring in the changes you have made that would make the preload stay the same as before since the pushrod is being pushed into the lifter just as much as before. I dont know the answer to your question but I would think you would be just right by doing that.
08-27-2008, 09:09 PM
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By taking the factory measurments and figuring in the changes you have made that would make the preload stay the same as before since the pushrod is being pushed into the lifter just as much as before. I dont know the answer to your question but I would think you would be just right by doing that.
