3 Bearing cam in a 4 bearing head

[gtblast]

I want to use a 3 bearing solid lifter cam in a 4 bearing head. I know I need to block off the unused bearing oil supply hole. One way is to rotate the unused cam bearing to cover the hole. Does anyone have any good ideas as to how to rotate that bearing? The only way I see is to remove it, rotate it, and press it back in. Or, is there another simple way to block off the oil feed hole?

[jeff denton]

I've done a lot of head scratching and tinkering in the cam/head/oiling system, and have decided I like four bearings best, but only when externally oiled as in my yet unpatented (and uncopied, I think) oil header system. I'm sure the fourth bearing leaks just enough more oil than the third to cause not enough oil to reach all the way back. You can see it in lifter wear, they get progressively worse front to rear. This has been commonly solved by the "big puddle" method, the oil drain riser.
I used a four bearing cam in my three bearing H head, because our resident expert says the fourth bearing just isn't that necessary until you get into really wild rpms and more valve lift which causes the need for stiffer springs. So I wouldn't be afraid to do what you're thinking, I know it's been done, but yes you do want to make damn sure there's no oil wasted from the gallery at the unused bearing.
To answer your question (finally) I am certain the passage to the cam bearing could be drilled and tapped and plugged from above, do this by first drilling out the plug above it. The hole where the plug was can be tapped and plugged afterwards. It's a straight shot from the plug to the bearing's oil hole, that's how said hole was drilled to begin with, looks like the only reason the plug is there. There is talk in some thread about those plugs really should be drilled and replaced with pipe plugs anyway, they have been known to pop out, apparently. Same with the bigger ones on front and back of the gallery.
That's how I would do it. My header system involves drilling and tapping the plug, I know that part is simple.
I just hope it gets caught before you or someone else then swaps in the four bearing cam someday. It could happen.

[gtblast]

Originally Posted by jeff denton I've done a lot of head scratching and tinkering in the cam/head/oiling system, and have decided I like four bearings best, but only when externally oiled as in my yet unpatented (and uncopied, I think) oil header system. I'm sure the fourth bearing leaks just enough more oil than the third to cause not enough oil to reach all the way back. You can see it in lifter wear, they get progressively worse front to rear. This has been commonly solved by the "big puddle" method, the oil drain riser. I used a four bearing cam in my three bearing H head, because our resident expert says the fourth bearing just isn't that necessary until you get into really wild rpms and more valve lift which causes the need for stiffer springs. So I wouldn't be afraid to do what you're thinking, I know it's been done, but yes you do want to make damn sure there's no oil wasted from the gallery at the unused bearing. To answer your question (finally) I am certain the passage to the cam bearing could be drilled and tapped and plugged from above, do this by first drilling out the plug above it. The hole where the plug was can be tapped and plugged afterwards. It's a straight shot from the plug to the bearing's oil hole, that's how said hole was drilled to begin with, looks like the only reason the plug is there. There is talk in some thread about those plugs really should be drilled and replaced with pipe plugs anyway, they have been known to pop out, apparently. Same with the bigger ones on front and back of the gallery. That's how I would do it. My header system involves drilling and tapping the plug, I know that part is simple. I just hope it gets caught before you or someone else then swaps in the four bearing cam someday. It could happen.

This is exactly what I was thinking. I have already removed the plugs and drilled and tapped the holes for screw in plugs. It seems I could just go right through the drilled out hole and drill and tap a plug inside to plug up the bearing hole. Should be easy, certainly eaiser than trying to rotate that bearing.

[hrcollinsjr]

Originally Posted by gtblast This is exactly what I was thinking. I have already removed the plugs and drilled and tapped the holes for screw in plugs. It seems I could just go right through the drilled out hole and drill and tap a plug inside to plug up the bearing hole. Should be easy, certainly eaiser than trying to rotate that bearing.

Sounds like a lot of extra work. I do agree with drilling and tapping the holes where the Al plugs are as I've replaced two that popped out on there own. Any engine shop should be able to rotate the 3rd cam bearing for you. It is a simple tool that expands inside the bearing and pulls the bearing in slide hammer like fashion. Rotate slightly and reinstall. I've not done it as I didn't have the tool but I've washed it being done.

Harold

[wrench459]

Originally Posted by gtblast I want to use a 3 bearing solid lifter cam in a 4 bearing head. I know I need to block off the unused bearing oil supply hole. One way is to rotate the unused cam bearing to cover the hole. Does anyone have any good ideas as to how to rotate that bearing? The only way I see is to remove it, rotate it, and press it back in. Or, is there another simple way to block off the oil feed hole?

For a little over 100 bucks you can get any solid lifter cam profile imagineable for the four bearing head. I tend to like the four bgr. heads because there more stable with the cam timing at higher rpm. Think of it this way the camshaft will flex some..at higher rpms the cam events on three and four cylinders will retard some especially with high spring pressure.
Now if your going to rotate #3 cam bgr. your first going to need to remove # 4.
You could drill out the oil passage an insert a plug under the oil galley but I dont see a good reason unless you've got a special camshaft.