Lifter and spring failure.. Which came first? UPDATE
Lifter and spring failure.. Which came first? UPDATE So my wife's WS.6 dropped a valve recently (https://ls1tech.com/forums/generatio...ow-update.html), and i thought it was due to the 918s. Got the head pulled off, and now im not so sure. Would a spring failure cause this damage to the lifter?
Click on Pics
Spring
Rocker arm. The sides are pushed out somehow. The one on the left is from the failed spring.
Heres what i found when i got the head off:
I found the retainer clip out of the top of the lifter IN the lifter tray, and the cup inside the top of the lifter was cocked to the side, where it is broken out.
Heres a shot of the piston.
Heres the head of the valve. I found the stem in the intake manifold.
All your input is appreciated!!
UPDATE:: Just checked a couple springs, and they were both about 125#s at installed height(1.8"), and over 300# at 1.2".
Click on Pics
Spring
Rocker arm. The sides are pushed out somehow. The one on the left is from the failed spring.
Heres what i found when i got the head off:
I found the retainer clip out of the top of the lifter IN the lifter tray, and the cup inside the top of the lifter was cocked to the side, where it is broken out.
Heres a shot of the piston.
Heres the head of the valve. I found the stem in the intake manifold.
All your input is appreciated!!
UPDATE:: Just checked a couple springs, and they were both about 125#s at installed height(1.8"), and over 300# at 1.2".
Last edited by NVR_SPDS; Feb 24, 2011 at 11:48 AM.
Not sure but I would carefully inspect all the other parts to see if you can find something wrong that might indicate where this started. Also test the good springs to see what they have left for stiffness. Check the pushrod cups in the rockers to see if they have signs of impact (pushrod losing contact).
Bent pushrod may have caused the lifter failure, which may have bent due to float. I think testing the springs will be a key piece of information.
Bent pushrod may have caused the lifter failure, which may have bent due to float. I think testing the springs will be a key piece of information.
Not sure but I would carefully inspect all the other parts to see if you can find something wrong that might indicate where this started. Also test the good springs to see what they have left for stiffness. Check the pushrod cups in the rockers to see if they have signs of impact (pushrod losing contact).
Bent pushrod may have caused the lifter failure, which may have bent due to float. I think testing the springs will be a key piece of information.
Bent pushrod may have caused the lifter failure, which may have bent due to float. I think testing the springs will be a key piece of information.
Yup, Comp Cams PRs.
The spring most likely broke first, causing the valve to hang open and get smacked by the piston. When the piston jammed the valve closed it bottomed out the PR in the lifter cup and broke the lifter.
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Spring broke.
Nothing wrong with hardned PR. Used them for years on Ford stuff the problem is using single springs. All heck breaks loose when one fails not a fault of the PR
Tim
Nothing wrong with hardned PR. Used them for years on Ford stuff the problem is using single springs. All heck breaks loose when one fails not a fault of the PR
Tim
It can be argued that GM used the PR's they did because PR flex is not an issue with OEM spring pressure.....The stock setup doesn't NEED anything stronger (the REASON)
But when you go with a big cam that requires a high spring rate for valvetrain control the stockers flex and actually CAUSE valvetrain instability and weird harmonics..
If you just run a properly matched setup and change the springs when you should hardened PR's are great. I have the slightly larger 3/8" PR's in my motor and TEA Golds with over 430lbs. (IIRC) open pressure so a stock PR wouldn't fare too well for me....
But when you go with a big cam that requires a high spring rate for valvetrain control the stockers flex and actually CAUSE valvetrain instability and weird harmonics..
If you just run a properly matched setup and change the springs when you should hardened PR's are great. I have the slightly larger 3/8" PR's in my motor and TEA Golds with over 430lbs. (IIRC) open pressure so a stock PR wouldn't fare too well for me....
On The Tree
Joined: Sep 2008
Posts: 180
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From: Virgina Beach
What did the inner "arm pit" of the rocker look like? My girlfriends '68 vette did this with a built up 355. The rocker arm came down on the upper spring retainer which broke, than the spring broke. Took the head off and it looked exactly like your pics. Her's had domed pistons though. Wasn't very domed after that. Sorry to see that.
Launching!
Joined: Nov 2010
Posts: 251
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OEM pushrods are cheap and fit the bill for low spring rates, end of story.
What do you think the hardening of pushrods is for?
Some of the issues with valve train is not using a strong enough push rod. Under load and RPM they turn into a wet noodle. This is the second biggest reason guys have issues. You want the bigest dia with a thick wall for best performance as the spring pressure and ramp speed goes up.
If this is done correctly you should never have to worrey about breaking stuff.
Tim
Some of the issues with valve train is not using a strong enough push rod. Under load and RPM they turn into a wet noodle. This is the second biggest reason guys have issues. You want the bigest dia with a thick wall for best performance as the spring pressure and ramp speed goes up.
If this is done correctly you should never have to worrey about breaking stuff.
Tim
Everyone is quick to blame the spring so I'll be the one to look at it from other side of the pushrod. People have found the lifter clips stuck to the drain plug and got a lucky break. What if your lifter lost it's clip allowing the cup to twist from under the pushrod. This could break the top of the lifter and take the tray out with it. Now the pushrod falls out of the rocker cup and catches the side of the rocker when it opens again. This could coil bind and break the spring which would now allow the valve to drop.
It's easy to quickly blame the spring as they got such a bad rep in the years past with bad batches and high failure rates. But I think that has been resolved and what has happened here is not a spring failure issue(at least not directly).
It's easy to quickly blame the spring as they got such a bad rep in the years past with bad batches and high failure rates. But I think that has been resolved and what has happened here is not a spring failure issue(at least not directly).
And bent stock pushrods are for wearing through intake runners. Ask any GM mechanic how many bent or broken stock pushrods he has replaced.