Is this ls7 lifter preload good or bad?
10-03-2008, 08:24 PM
#1
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Is this ls7 lifter preload good or bad? Ok, i followed all your instructions on how to set preload on a non adjustable rocker, and this is what i came up with.
Zero lash with pushrod tester was 11.75 turns x .050 for each turn = .05875
.05875 + the pushrod tester all the way closed which is 6.800 +.05875
which equals the total pushrod length of 7.3875. now i add in the lifter preload. I currently have a set of pushrods of 7.500 which if i use these i subtract the 7.500 from the 7.3875 zero lash pushrod, i would get a preload of .1125 or just .112. So to be more clear , the 7.500 pushrod would give me a preload of .112.
Now, i was told by another member who said that ( " with ls7 lifters you can run alot of preload without worry and it will give me power due to better valve control in the higher rpm range " . He also said that gm recommended preload is .60 - .100, but that .120-.140 preload seems to work better ". ) He went on to say that my 7.5 pushrods would be about the right length, but that i should still get shims to correct the geometry of the roller to the valve tip.
Is this info accurate? can these lifters work safely with a preload of 112 , or should i be lower. any other suggestions about a shim size or anything else would be welcome.
Zero lash with pushrod tester was 11.75 turns x .050 for each turn = .05875
.05875 + the pushrod tester all the way closed which is 6.800 +.05875
which equals the total pushrod length of 7.3875. now i add in the lifter preload. I currently have a set of pushrods of 7.500 which if i use these i subtract the 7.500 from the 7.3875 zero lash pushrod, i would get a preload of .1125 or just .112. So to be more clear , the 7.500 pushrod would give me a preload of .112.
Now, i was told by another member who said that ( " with ls7 lifters you can run alot of preload without worry and it will give me power due to better valve control in the higher rpm range " . He also said that gm recommended preload is .60 - .100, but that .120-.140 preload seems to work better ". ) He went on to say that my 7.5 pushrods would be about the right length, but that i should still get shims to correct the geometry of the roller to the valve tip.
Is this info accurate? can these lifters work safely with a preload of 112 , or should i be lower. any other suggestions about a shim size or anything else would be welcome.
Last edited by wilwhite2kss; 10-03-2008 at 08:29 PM.
10-04-2008, 03:04 PM
#3
TECH Addict
I think if that's your measurement (do at least three valves to double check) you should be fine. If it runs well, and should be nice and quiet, then you're good to go. If not, the next step is 7.475s which would put you at .087.
