Metal in oil - Valve seal carnage
10-09-2018, 05:28 AM
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Metal in oil - Valve seal carnage Recently performed a spring swap in my LS7 427. PAC1206X with new retainers, locks, seals etc (all from PAC). Cam is .651" lift. PAC and CAM company recommended install height of 1.75". To get to this install height required ALOT OF SHIMS, varying on each valve. In some cases .180" of shims was needed. I used a PAC spring micrometer and verified height multiple times. I called PAC and asked if there is a problem using this many shims and they said no, there should not be. The seals were installed fully and correctly and pressed down using a BTR seal install tool. Springs were installed/removed using an LSM Racing SC-167 Valve spring removal tool (nice little tool by the way). Locks were all in place, lash caps were installed on intake valves. Springs that came off were were PAC1209X with no shims (installed by someone else).
Ran the car for about 500 miles. No issues. No weird noises or smoke or anything. Car ran great. Pulled spark plugs to check condition and 4 spark plugs had significant amounts of oil on the threads (never there before and I check regularly). Dumped the oil and found ALOT of metal fragments which appeared to be valve seals. Pulled the valve covers and started pulling springs. Found 4 valve seals either crushed from the top or literally gone! All springs (inner and outer) were in perfect condition. Retainers look perfect. Locators look at little marred but OKAY. Valves are fine and no wiggling (new guides last year). But the new seals are all beat to hell, busted, broken or literally gone.
I called PAC and they don't know why. I asked if using this many shims could somehow cause interference and they said possibly. They said to try to remove 50 thou worth of shims and run it. This would bring install height to 1.80" (where my last springs were installed).
Can anyone offer some suggestions or guidance as to why/how this happened? No one that I have talked to seems to know. If it was one seal damaged I could maybe attribute to a freak occurrence. But 4 of them are either smashed from the top or literally just gone/destroyed....3 intake and one exhaust on various cylinders. Could this many shims cause a problem? I've done alot of reading and found this happemed to other guys but never read about a solution despite many suggestions and experimenting (different style seals etc).
Appreciate in advance any tips or suggestions. I ordered 16 new seals but don't just want to press them back in as it is clear it will likely happen again and I don't know why. Should I remove 50 thou worth of shims and try that?
Ran the car for about 500 miles. No issues. No weird noises or smoke or anything. Car ran great. Pulled spark plugs to check condition and 4 spark plugs had significant amounts of oil on the threads (never there before and I check regularly). Dumped the oil and found ALOT of metal fragments which appeared to be valve seals. Pulled the valve covers and started pulling springs. Found 4 valve seals either crushed from the top or literally gone! All springs (inner and outer) were in perfect condition. Retainers look perfect. Locators look at little marred but OKAY. Valves are fine and no wiggling (new guides last year). But the new seals are all beat to hell, busted, broken or literally gone.
I called PAC and they don't know why. I asked if using this many shims could somehow cause interference and they said possibly. They said to try to remove 50 thou worth of shims and run it. This would bring install height to 1.80" (where my last springs were installed).
Can anyone offer some suggestions or guidance as to why/how this happened? No one that I have talked to seems to know. If it was one seal damaged I could maybe attribute to a freak occurrence. But 4 of them are either smashed from the top or literally just gone/destroyed....3 intake and one exhaust on various cylinders. Could this many shims cause a problem? I've done alot of reading and found this happemed to other guys but never read about a solution despite many suggestions and experimenting (different style seals etc).
Appreciate in advance any tips or suggestions. I ordered 16 new seals but don't just want to press them back in as it is clear it will likely happen again and I don't know why. Should I remove 50 thou worth of shims and try that?
10-09-2018, 11:05 AM
#2
I’m surprised PAC couldn’t give you an answer as to why this happened. It sounds to me like adding that amount of shims caused you to not have enough retainer to seal clearance with the valves at max lift. No fault of the springs, I just think this set might not be the right choice for your application. What was the final installed height with .180” shims? If it’s anywhere near the recommended 1.8” then you will likely need a longer spring set for your application. Maybe in the 1.9-2.0” installed height range.
That being said there are a few critical measurements you need to verify when installing new valve springs, and you only mentioned installed height (which is a good start!). Retainer to seal clearance is typically calculated from installed height and cam lift, but in this case it’s obvious there wasn’t enough clearance. Your choice would be longer springs or machining your valve guides to provide more clearance. Did you check for coil bind as well?
That being said there are a few critical measurements you need to verify when installing new valve springs, and you only mentioned installed height (which is a good start!). Retainer to seal clearance is typically calculated from installed height and cam lift, but in this case it’s obvious there wasn’t enough clearance. Your choice would be longer springs or machining your valve guides to provide more clearance. Did you check for coil bind as well?
10-09-2018, 12:00 PM
#3
Sounds kinda like an installation problem. Improper height measurement somehow. That's WWWWWAAAAAAAAAYYYYYY more shim than it should have taken.
Factory springs are about 1.8" when used with the seals that include a spring seat, which is around .030" at most. I'd be expecting around .080" to get to 1.75" installed height therefore. .180" of shim doesn't sound right at all.
Factory springs are about 1.8" when used with the seals that include a spring seat, which is around .030" at most. I'd be expecting around .080" to get to 1.75" installed height therefore. .180" of shim doesn't sound right at all.
10-09-2018, 12:06 PM
#4
Sounds kinda like an installation problem. Improper height measurement somehow. That's WWWWWAAAAAAAAAYYYYYY more shim than it should have taken.
Factory springs are about 1.8" when used with the seals that include a spring seat, which is around .030" at most. I'd be expecting around .080" to get to 1.75" installed height therefore. .180" of shim doesn't sound right at all.
Factory springs are about 1.8" when used with the seals that include a spring seat, which is around .030" at most. I'd be expecting around .080" to get to 1.75" installed height therefore. .180" of shim doesn't sound right at all.
10-09-2018, 02:03 PM
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Thanks much for the replies. Springs were installed at 1.75" per PAC recommendations based on the lift of my cam and the required pressure open and closed . I personally measured the install height with the PAC spring micrometer from spring locator to bottom of retainer and verified it with my digital gauge. At 1.75" install height it should have gotten me to .099" from coil bind.
1.00" coil bind + .651" lift + .099" clearance = 1.75" install height. That sound right? No idea why it took so many shims, but that's how many it took to get to 1.75" height. I even called PAC when I realized I needed ALOT of shims and they actually sent me more and said it shouldn't be a problem.
Valve seals were PAC valve seals spec'd for my springs. I bought an entire kit from them that included retainers, locators, seals, springs etc. I'm thinking I should remove 50 thou worth of shims to get to 1.8" but I am not sure if that solves my problem of destroying seals. I don't even understand why it is happening to begin with and neither does anyone else that has looked at it.
Edit: I will measure the retainer to seal clearance. Perhaps the retainer is hitting the seal? Should it be at least my lift + .050"?
1.00" coil bind + .651" lift + .099" clearance = 1.75" install height. That sound right? No idea why it took so many shims, but that's how many it took to get to 1.75" height. I even called PAC when I realized I needed ALOT of shims and they actually sent me more and said it shouldn't be a problem.
Valve seals were PAC valve seals spec'd for my springs. I bought an entire kit from them that included retainers, locators, seals, springs etc. I'm thinking I should remove 50 thou worth of shims to get to 1.8" but I am not sure if that solves my problem of destroying seals. I don't even understand why it is happening to begin with and neither does anyone else that has looked at it.
Edit: I will measure the retainer to seal clearance. Perhaps the retainer is hitting the seal? Should it be at least my lift + .050"?
Last edited by bnab427; 10-09-2018 at 02:24 PM.
10-09-2018, 02:26 PM
#7
Thanks much for the replies. Springs were installed at 1.75" per PAC recommendations based on the lift of my cam and the required pressure open and closed . I personally measured the install height with the PAC spring micrometer from spring locator to bottom of retainer and verified it with my digital gauge. At 1.75" install height it should have gotten me to .099" from coil bind.
1.00" coil bind + .651" lift + .099" clearance = 1.75" install height. That sound right? No idea why it took so many shims, but that's how many it took to get to 1.75" height. I even called PAC when I realized I needed ALOT of shims and they actually sent me more and said it shouldn't be a problem.
Valve seals were PAC valve seals spec'd for my springs. I bought an entire kit from them that included retainers, locators, seals, springs etc. I'm thinking I should remove 50 thou worth of shims to get to 1.8" but I am not sure if that solves my problem of destroying seals. I don't even understand why it is happening to begin with and neither does anyone else that has looked at it.
1.00" coil bind + .651" lift + .099" clearance = 1.75" install height. That sound right? No idea why it took so many shims, but that's how many it took to get to 1.75" height. I even called PAC when I realized I needed ALOT of shims and they actually sent me more and said it shouldn't be a problem.
Valve seals were PAC valve seals spec'd for my springs. I bought an entire kit from them that included retainers, locators, seals, springs etc. I'm thinking I should remove 50 thou worth of shims to get to 1.8" but I am not sure if that solves my problem of destroying seals. I don't even understand why it is happening to begin with and neither does anyone else that has looked at it.
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10-09-2018, 02:34 PM
#8
That sound right?
"Coil bind" and "seal clearance" have NOTHING WHATSOEVER to do with each other. Which ultimately also means, how much shim you use, shouldn't affect seal clearance.
Or for that matter really, whether it's a LS7 or what... 1.800" or whatever, is 1.800".
Here we go, right straight off of PAC's web site https://www.racingsprings.com/index....s-springs.html though, FWIW:
Part# OD IH Load at IH Recommended Valve Lift
PAC-1209X 1.324 1.800 160 0.750
I don't know why they would have told you to use 1.750" instead, but I can't see where that, in and of itself, would be an issue, as long as they don't coil-bind.
A great place to start might be to put some real light "checking" springs in there, and see what the clearance from the bottom of the retainer to the top of the seal is. You might just simply have too much cam for the heads, without either: cutting the guides down to give it room; or, installing longer valves; or, using offset keepers.
But really, I'm suspecting there's a height measurement problem somewhere. How you're using the spring mic or that sort of thing maybe.