GoFaster
Crush fitting works well in steel rods with steel backed bearings or cast iron blocks with pressed in steel backed bearings. But even then the term spun bearing / bearings comes up at times. Aluminum rods do use steel backed bearings, but often use shuffle pins to keep down problems. VW air cooled engines used shuffle pins in the magnesium block to maintain bearing position. Metals with different expansion rates are hard to make use high crush values. My belt end cam bearings had turned in the head about .060" US.
You have said the cam is not under constant loading, goes all over the place when running. There are no marks on the cam bearings to show contact toward the top of the engine (top cam bearing marks especially the center three) or on the rear side of the lower cam bearings. The marks show stable position to me. That is not to say the cam does not move, I just see no signs of this movement you describe. My cam bearings are slick and smooth ( no chatter signs) , only show copper wear in one place, and show no top or rear signs of wear (you will have to take my word for the top bearings are still in the engine). The top end bearings on the high wear set) do show IMHO cocking wear in the worn set.
You related the entire top of the engine might be starving for oil. There are no complaints of follower clatter / ticking till just before the follower tops wear through or crack to bleed off oil the last few miles / time period.
Since the lower end does not usually fail when the follower tops wear out, the restriction must be about correct to the head. Correct restriction keeps lower end bearing failure from happening with head problems. No clatter problems shows the restriction is close to correct. I realize there are mentions of clatter right before the engines start missing, but for thousands of miles there is not a common complaint (that I have heard).
Loose fit of the followers should oil the tops better and cause clatter if oil was limited, but the followers do not clatter and follower tops seem dry.
If cam bearings are too close then we should see marks. Since we see no marks they must be loose, but since mine looked pretty good at 107,000 miles US they must have been oiling fair till that point. My lobes were starting to show copper streaks though . Changed out cam bearings restored the cam looks.
I covered the oil pressure comparison on post #31 and agree with you.
The injection roller seems to hold the cam very stable (no ramble marks like the ALH). Enough oil is available till something happens.
I really need to cut some bearings and get them in, but a deep valve cover (inspection tool) is still something I do not have.
eddif
Crush fitting works well in steel rods with steel backed bearings or cast iron blocks with pressed in steel backed bearings. But even then the term spun bearing / bearings comes up at times. Aluminum rods do use steel backed bearings, but often use shuffle pins to keep down problems. VW air cooled engines used shuffle pins in the magnesium block to maintain bearing position. Metals with different expansion rates are hard to make use high crush values. My belt end cam bearings had turned in the head about .060" US.
You have said the cam is not under constant loading, goes all over the place when running. There are no marks on the cam bearings to show contact toward the top of the engine (top cam bearing marks especially the center three) or on the rear side of the lower cam bearings. The marks show stable position to me. That is not to say the cam does not move, I just see no signs of this movement you describe. My cam bearings are slick and smooth ( no chatter signs) , only show copper wear in one place, and show no top or rear signs of wear (you will have to take my word for the top bearings are still in the engine). The top end bearings on the high wear set) do show IMHO cocking wear in the worn set.
You related the entire top of the engine might be starving for oil. There are no complaints of follower clatter / ticking till just before the follower tops wear through or crack to bleed off oil the last few miles / time period.
Since the lower end does not usually fail when the follower tops wear out, the restriction must be about correct to the head. Correct restriction keeps lower end bearing failure from happening with head problems. No clatter problems shows the restriction is close to correct. I realize there are mentions of clatter right before the engines start missing, but for thousands of miles there is not a common complaint (that I have heard).
Loose fit of the followers should oil the tops better and cause clatter if oil was limited, but the followers do not clatter and follower tops seem dry.
If cam bearings are too close then we should see marks. Since we see no marks they must be loose, but since mine looked pretty good at 107,000 miles US they must have been oiling fair till that point. My lobes were starting to show copper streaks though . Changed out cam bearings restored the cam looks.
I covered the oil pressure comparison on post #31 and agree with you.
The injection roller seems to hold the cam very stable (no ramble marks like the ALH). Enough oil is available till something happens.
I really need to cut some bearings and get them in, but a deep valve cover (inspection tool) is still something I do not have.
eddif