Help with lifter tick on fresh rebuild?
07-31-2020, 06:22 PM
#12
TECH Enthusiast
Thread Starter
I’m honestly not 100% that I did it correctly, but what I got made me think 7.4 would be fine.
It doesn’t seem to be noisy anywhere but #7, wouldn’t they all tick if the length was off?
08-01-2020, 10:58 AM
#13
Not necessarily; if the one valve on #7 didn't have its seat cut as deep, or if it had part of its tip cut off to eliminate damage, it could easily be different.
Best thing to do would be, first, try to identify which one it is, by listening with the valve covers off. Yeah I know, more easily said than done, but if you can wangle it, good place to start.
Correct way to use the adj PR is, screw it all the way together, and then unscrew it some # of turns to bring its length to somewhat short of the most likely expectation (e.g. with a Comp 7702, 6.800" fully screwed together, .050" per turn; 10 turns out would be 7.300"); rotate the engine to where the one particular valve is on the cam base circle, either by the EOIC method, or by the 4-cyls-away-in-the-firing-order method (NOT the "Chilton's" method, where you "measure" 8 valves with the engine at one place, and the other 8 with it at another); install that rocker and the adj PR; check the rocker for up/down ply; if it has some, remove the rocker, unscrew the PR 1 full turn if it has "alot" or ½ turn if has has "just a little" (PRs you can readily buy off the shelf come in .025" increments, so it makes sense to set your adj in the same steps); continue until you find the length that has a TINY amount of play, and the next .025" increment is FULLY TIGHT; add the top end of your desired preload, range which is dependent on the lifters you have, to the longest length that still has play; and purchase. Target preload range might be .040" - .060" with the older stock LS1 lifters, .075" - .090" with LS7, .020" with Johnson, etc.; you need to know what your particular lifters want. Check several of course, including your problem one(s) if any. Ideally all 16 can be brought within the desired range with all 16 PRs the same length, but if not, oh well.
7.4" is stock length, and seems to me like it would more likely be too long for a cam with that much lift, but that's by no means any kind of an absolute. Just, "likely". Too short would be more likely to create a tick rather than too long though. Alternatively you may have some cause of a tick other than PR length; a groove worn in a rocker tip that the edge rides up on the valve stem during part of the travel and then "falls off" so to speak, for example. Or a spring rubbing on something as it compresses... I once had what I thought was a tick in a motor with solids, but then as I was adjusting the lifters, heard a "rrrrrrrrreeeeeeeeeeeeeeekkkk" kind of sound as I turned the motor by hand, and upon detailed investigation it turned out to be a spring (these were double with a damper), where the inner was rubbing on the inside of the damper. I swapped acoupla springs around and it cleared up, I guess maybe one of the spring pads on the head wasn't EXACTLY perpendicular to the valve, or something, and that specific spring was sensitive to it in some way. It's not impossible you have something weird like that going on.
Best thing to do would be, first, try to identify which one it is, by listening with the valve covers off. Yeah I know, more easily said than done, but if you can wangle it, good place to start.
Correct way to use the adj PR is, screw it all the way together, and then unscrew it some # of turns to bring its length to somewhat short of the most likely expectation (e.g. with a Comp 7702, 6.800" fully screwed together, .050" per turn; 10 turns out would be 7.300"); rotate the engine to where the one particular valve is on the cam base circle, either by the EOIC method, or by the 4-cyls-away-in-the-firing-order method (NOT the "Chilton's" method, where you "measure" 8 valves with the engine at one place, and the other 8 with it at another); install that rocker and the adj PR; check the rocker for up/down ply; if it has some, remove the rocker, unscrew the PR 1 full turn if it has "alot" or ½ turn if has has "just a little" (PRs you can readily buy off the shelf come in .025" increments, so it makes sense to set your adj in the same steps); continue until you find the length that has a TINY amount of play, and the next .025" increment is FULLY TIGHT; add the top end of your desired preload, range which is dependent on the lifters you have, to the longest length that still has play; and purchase. Target preload range might be .040" - .060" with the older stock LS1 lifters, .075" - .090" with LS7, .020" with Johnson, etc.; you need to know what your particular lifters want. Check several of course, including your problem one(s) if any. Ideally all 16 can be brought within the desired range with all 16 PRs the same length, but if not, oh well.
7.4" is stock length, and seems to me like it would more likely be too long for a cam with that much lift, but that's by no means any kind of an absolute. Just, "likely". Too short would be more likely to create a tick rather than too long though. Alternatively you may have some cause of a tick other than PR length; a groove worn in a rocker tip that the edge rides up on the valve stem during part of the travel and then "falls off" so to speak, for example. Or a spring rubbing on something as it compresses... I once had what I thought was a tick in a motor with solids, but then as I was adjusting the lifters, heard a "rrrrrrrrreeeeeeeeeeeeeeekkkk" kind of sound as I turned the motor by hand, and upon detailed investigation it turned out to be a spring (these were double with a damper), where the inner was rubbing on the inside of the damper. I swapped acoupla springs around and it cleared up, I guess maybe one of the spring pads on the head wasn't EXACTLY perpendicular to the valve, or something, and that specific spring was sensitive to it in some way. It's not impossible you have something weird like that going on.
Last edited by RB04Av; 08-01-2020 at 04:40 PM.
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Nick99Chevy (08-02-2020)
08-01-2020, 04:36 PM
#14
Dayumm, I just noticed the forum hammered the abbreviation for "Push Rod"... put it in a white font. 
OK, so, wherever you see a REAL WIDE gap in my post, mentally insert P R there.
Maybe it thinks it's a racial/ethnic slur? Iunno.
OK, so, wherever you see a REAL WIDE gap in my post, mentally insert P R there.Maybe it thinks it's a racial/ethnic slur? Iunno.
08-02-2020, 09:50 AM
#17
TECH Enthusiast
Thread Starter
So I went back through the lifter adjustment using the EO/IC method I found and the preload is
set to about .059 now. No abnormal wear on anything, I checked all pushrods and lifters. Fired it
back up, no change. So out it came again.
Compared to the other, it looks like #7 wasn’t firing much. Would you expect a little metallic residue
in the pan after a first run?
set to about .059 now. No abnormal wear on anything, I checked all pushrods and lifters. Fired it
back up, no change. So out it came again.
Compared to the other, it looks like #7 wasn’t firing much. Would you expect a little metallic residue
in the pan after a first run?
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