Valves push open when lashing rocker arms?
11-09-2014, 11:19 AM
#1
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Valves push open when lashing rocker arms? I was verifying how many turns from zero lash and noticed something I wasn't expecting.
Once at zero lash, when I tighten the rocker arm bolt - the valve is being pushed open...then over the next 10 - 15 seconds the valve spring slowly overcomes the lifter and pushes the valve closed.
What the hell? Is this normal? I repeatedly checked and when I break the rocker loose the valve is definitely in the seated position, but when I tighten the rocker back down the valve spring "gives" before the lifter.
LS7 lifters, OEM rockers, PAC double springs with 6K miles on them and no signs of valve float. Over 200psi compression on a cold motor with a leaky compression tester.
Once at zero lash, when I tighten the rocker arm bolt - the valve is being pushed open...then over the next 10 - 15 seconds the valve spring slowly overcomes the lifter and pushes the valve closed.
What the hell? Is this normal? I repeatedly checked and when I break the rocker loose the valve is definitely in the seated position, but when I tighten the rocker back down the valve spring "gives" before the lifter.
LS7 lifters, OEM rockers, PAC double springs with 6K miles on them and no signs of valve float. Over 200psi compression on a cold motor with a leaky compression tester.
Last edited by 74u; 11-09-2014 at 11:29 AM.
11-09-2014, 01:09 PM
#3
I was verifying how many turns from zero lash and noticed something I wasn't expecting.
Once at zero lash, when I tighten the rocker arm bolt - the valve is being pushed open...then over the next 10 - 15 seconds the valve spring slowly overcomes the lifter and pushes the valve closed.
What the hell? Is this normal? I repeatedly checked and when I break the rocker loose the valve is definitely in the seated position, but when I tighten the rocker back down the valve spring "gives" before the lifter.
LS7 lifters, OEM rockers, PAC double springs with 6K miles on them and no signs of valve float. Over 200psi compression on a cold motor with a leaky compression tester.
Once at zero lash, when I tighten the rocker arm bolt - the valve is being pushed open...then over the next 10 - 15 seconds the valve spring slowly overcomes the lifter and pushes the valve closed.
What the hell? Is this normal? I repeatedly checked and when I break the rocker loose the valve is definitely in the seated position, but when I tighten the rocker back down the valve spring "gives" before the lifter.
LS7 lifters, OEM rockers, PAC double springs with 6K miles on them and no signs of valve float. Over 200psi compression on a cold motor with a leaky compression tester.
11-09-2014, 02:01 PM
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From zero lash it's 1.25 - 1.5 turns to seat the rocker...then a little more to hit 22ft.lbs....should be about right.
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11-09-2014, 07:46 PM
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My initial thought was the pushrods must be too long, but they seem to be in the range (from zero lash 1.25 - 1.5 turns to seat the rocker in the rocker stand).
11-10-2014, 05:15 AM
#11
i was verifying how many turns from zero lash and noticed something i wasn't expecting.
Once at zero lash, when i tighten the rocker arm bolt - the valve is being pushed open...then over the next 10 - 15 seconds the valve spring slowly overcomes the lifter and pushes the valve closed.
What the hell? Is this normal? I repeatedly checked and when i break the rocker loose the valve is definitely in the seated position, but when i tighten the rocker back down the valve spring "gives" before the lifter.
Ls7 lifters, oem rockers, pac double springs with 6k miles on them and no signs of valve float. Over 200psi compression on a cold motor with a leaky compression tester.
Once at zero lash, when i tighten the rocker arm bolt - the valve is being pushed open...then over the next 10 - 15 seconds the valve spring slowly overcomes the lifter and pushes the valve closed.
What the hell? Is this normal? I repeatedly checked and when i break the rocker loose the valve is definitely in the seated position, but when i tighten the rocker back down the valve spring "gives" before the lifter.
Ls7 lifters, oem rockers, pac double springs with 6k miles on them and no signs of valve float. Over 200psi compression on a cold motor with a leaky compression tester.
its normal!
11-10-2014, 12:06 PM
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Who said we/I don't believe you
I've never noticed it on past builds and it caught my eye...but since it's holding over 200psi cranking compression and no air leak noises I'm inclined to think you are correct.
I've never noticed it on past builds and it caught my eye...but since it's holding over 200psi cranking compression and no air leak noises I'm inclined to think you are correct.
11-10-2014, 01:36 PM
#15
