Metal grit found in head
Metal grit found in head My valve train has been making too much noise IMO, so I took off the rocker cover to check the lifter preload, and when I did, I noticed some gray material sitting in a small pool of oil at the back of the head. I dug it out with my finger and found that it was metal grit, like fine sand. I tested with a magnet and found that it is steel, not aluminum. This can't be normal. I want to believe that this grit originated in the top of the head, since it seems to large to make it through an (A/C Delco) oil filter (I hope!) I'd hate to think this stuff went to my bearings too.
I also found that my preload is set WAY too high @ 0.150" on LS7 lifters! (My own fault) Can too much preload cause the lift to exceed the specs? In other words, if the spec'd lift is .595" with a 1.8 ratio rocker, can too much preload cause that to go higher than .595" from the lifter pumping up? I wouldn't think so, but ???
I'm wondering if this metal grit is from the valve springs possibly binding. The springs are PRC Gold, setup for .650 lift by TSP. The cam is a STOCK LS7 cam (< .600" lift).
I didn't find any signs of abnormal wear on the pushrod ball ends, or the rocker to valve contact points. And the rocker tip contact patch is in the center of the valve stem. I didn't take a close look at the springs.
These are LS7 heads BTW, if that makes a difference.
I also found that my preload is set WAY too high @ 0.150" on LS7 lifters! (My own fault) Can too much preload cause the lift to exceed the specs? In other words, if the spec'd lift is .595" with a 1.8 ratio rocker, can too much preload cause that to go higher than .595" from the lifter pumping up? I wouldn't think so, but ???
I'm wondering if this metal grit is from the valve springs possibly binding. The springs are PRC Gold, setup for .650 lift by TSP. The cam is a STOCK LS7 cam (< .600" lift).
I didn't find any signs of abnormal wear on the pushrod ball ends, or the rocker to valve contact points. And the rocker tip contact patch is in the center of the valve stem. I didn't take a close look at the springs.
These are LS7 heads BTW, if that makes a difference.
The rockers look great, with a good wear pattern. I was thinking about the lifter rollers and cam lobes too, but I can't imagine metal bits this large made it through the oiling system into the head, unless the bypass was open. Of course that would mean my bearings are now toast. Oil pressure isn't the greatest (20 PSI hot @ 500 RPM), but it hasn't been declining either.
Not sure how to check the bearings in the rockers, short of looking for missing needles. Maybe check for looseness? These were new LS7 rockers when installed, and so far have less than 500 miles. I do have the Comp trunion upgrade kit, just haven't had it installed yet. I suppose this would be a good time.
I do feel a need to inspect the cam/lifters. I'll probably end up just pulling the engine out so I can check everything.
I do feel a need to inspect the cam/lifters. I'll probably end up just pulling the engine out so I can check everything.
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