Lifter and spring failure.. Which came first? UPDATE
It's not the pushrod that causes the mess, it's whatever broke in the first place that causes a mess. Pushrods aren't meant to be fusible links in a performance engine. They're meant to be stiff an rigid in order to transmit motion to the valve more effectively. If you like using pushrods that can bend, then you must be pretty used to your **** blowing up.
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?
UPDATE:: Just checked a couple springs, and they were both about 125#s at installed height(1.8"), and over 300# at 1.2".
UPDATE:: Just checked a couple springs, and they were both about 125#s at installed height(1.8"), and over 300# at 1.2".
Judging by the way the rockers look and the broken spring, I'm supecting coilbind clearance. What are the installed heights and how close to coilbind is the spring at open?
Hmmmm...I know that cam. Are your pistons fly cut? What head gasket thickness are you using? Are the heads decked?
What is mentioned above seems possible (coil bind) or perhaps your intake valves were kissing the top of the pistons. Who set the engine up? That 231/237 cam lobe takes more rotation before the edge of the intake valve clears the piston. If the clearance was not checked w/clay, the issue could have gone un-noticed. A miss shift could also have cause the issue if the clearance was tight.
IIRC it was close to parallel to the roller. The break was towards the exhaust side of the head. Ill check installed heights. The cam is supposed to be just a hair under .600 lift.
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it's not the pushrod that causes the mess, it's whatever broke in the first place that causes a mess. Pushrods aren't meant to be fusible links in a performance engine. They're meant to be stiff an rigid in order to transmit motion to the valve more effectively. If you like using pushrods that can bend, then you must be pretty used to your **** blowing up.
Hmmmm...I know that cam. Are your pistons fly cut? What head gasket thickness are you using? Are the heads decked?
What is mentioned above seems possible (coil bind) or perhaps your intake valves were kissing the top of the pistons. Who set the engine up? That 231/237 cam lobe takes more rotation before the edge of the intake valve clears the piston. If the clearance was not checked w/clay, the issue could have gone un-noticed. A miss shift could also have cause the issue if the clearance was tight.
What is mentioned above seems possible (coil bind) or perhaps your intake valves were kissing the top of the pistons. Who set the engine up? That 231/237 cam lobe takes more rotation before the edge of the intake valve clears the piston. If the clearance was not checked w/clay, the issue could have gone un-noticed. A miss shift could also have cause the issue if the clearance was tight.
Best I can tell is installed height is close to 1.8", all I have here are calipers. Dont remember the coil mind height.
AKAIK, ts pretty much the stock longblock that came in the car. Stock 853s with the graphite gaskets, stock headbolts, and an ls6 intake. I bought it modded, so I'm not sure who built it but it appears to be professionally done. We've put approx 30k miles on this setup without an issue at all. Never been to the track either. Didn't notice any eyebrows in the pistons either but I clean em up and double check.
Best I can tell is installed height is close to 1.8", all I have here are calipers. Dont remember the coil mind height.
Best I can tell is installed height is close to 1.8", all I have here are calipers. Dont remember the coil mind height.
If they're stock 853's, never decked & are using graphite gaskets, then the clearance is OK. 30K could mean that it was indeed the broken spring that ocurred first. Engines with higher pressure/lift springs should be checked every 15-20K for fatigue. There are engines with high lift/pressure springs that have gone over 30k without needing a spring change, but, they should always be tested to be sure there are no issues.
If they're stock 853's, never decked & are using graphite gaskets, then the clearance is OK. 30K could mean that it was indeed the broken spring that ocurred first. Engines with higher pressure/lift springs should be checked every 15-20K for fatigue. There are engines with high lift/pressure springs that have gone over 30k without needing a spring change, but, they should always be tested to be sure there are no issues.
What kind of fatigue should i have been looking for?
I don't know of a rule of thumb, but would say that if any test more than a few percent less than original force, then change. The fact that there was a major failure would direct me to change 'em all.
As you've noted, have a look for any valve kisses in the piston tops, just to be sure. Again, not likely an issue w/stock heads & gasket, but I do know that that cam is near the limit for PTV clearance without fly cutting.
Man... that lifter if f'cked up. Really sorry to see it. Hope you're able to get all of the pieces out of the oil pan.
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I would say spring fatigue but its hard to say looking at pics and not having the parts in hand.
Someone already said it but spring broke, dropped valve, piston hit valve, jammed push rod back into lifter.
Sorry to see this
Someone already said it but spring broke, dropped valve, piston hit valve, jammed push rod back into lifter.
Sorry to see this
Personally, I think this may be the source of your issue. You should have around 140# on the seat and I would shoot for 400# over the nose. With those valuves I don't think that spring setup will properly control the valve train. That being the case, you will likely loft the lifters and damage the lifter and cam.
What was your installed height?
Personally, I think this may be the source of your issue. You should have around 140# on the seat and I would shoot for 400# over the nose. With those valuves I don't think that spring setup will properly control the valve train. That being the case, you will likely loft the lifters and damage the lifter and cam.
Personally, I think this may be the source of your issue. You should have around 140# on the seat and I would shoot for 400# over the nose. With those valuves I don't think that spring setup will properly control the valve train. That being the case, you will likely loft the lifters and damage the lifter and cam.
Last edited by KCS; Feb 25, 2011 at 10:32 AM.
I don't know of a rule of thumb, but would say that if any test more than a few percent less than original force, then change. The fact that there was a major failure would direct me to change 'em all.
As you've noted, have a look for any valve kisses in the piston tops, just to be sure. Again, not likely an issue w/stock heads & gasket, but I do know that that cam is near the limit for PTV clearance without fly cutting.
Man... that lifter if f'cked up. Really sorry to see it. Hope you're able to get all of the pieces out of the oil pan.
As you've noted, have a look for any valve kisses in the piston tops, just to be sure. Again, not likely an issue w/stock heads & gasket, but I do know that that cam is near the limit for PTV clearance without fly cutting.
Man... that lifter if f'cked up. Really sorry to see it. Hope you're able to get all of the pieces out of the oil pan.
What was your installed height?
Personally, I think this may be the source of your issue. You should have around 140# on the seat and I would shoot for 400# over the nose. With those valuves I don't think that spring setup will properly control the valve train. That being the case, you will likely loft the lifters and damage the lifter and cam.
Personally, I think this may be the source of your issue. You should have around 140# on the seat and I would shoot for 400# over the nose. With those valuves I don't think that spring setup will properly control the valve train. That being the case, you will likely loft the lifters and damage the lifter and cam.
Last edited by NVR_SPDS; Feb 25, 2011 at 10:10 PM.
