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In using the tube method you do not need to lubricate the lifters on the other side of the motor and you are restricting the lubricating of the lifters on the passenger side also. You are in effect turning the lubrication of the solid lifters into a splash lubrication.
Use of the crossover tube is to make sure there is oil on the driver side of the motor for the hydraulic lifters and to lubricate the front main bearing and number one rod and of course restricting the oil in the passenger side galley.
The reason that you do not need to tube the driver side when you are tubing the passenger side is that you are going to block the flow of oil to the driver side by plugging the feed from the number one main going up to the galley on the driver side.[/QUOT
The only thing I would add to this is if you had a specific reason to still want a limited amount of oil to the drivers side lifters, you could tube both sides of the block which is much cheaper than bushing, and then drill very small feed holes into the tube for each lifter bore.
But it would depend on individual requirements and lifter type.
Even though my new block has bushings, you could only bush the passenger side of the block to cut the lifter leakage and then with a pipe plug block the flow to the drivers side to cut the flow over there.
I elected to spend the extra money and bush both side because I wanted the drivers side wet , and to have limited flow to my edm feed roller lifters and at the front end of the drivers side galley I have a .025 bleeder hole there to feed oil to the Torrington bearing on my milodon gear drive.
So I would say it depends on individual requirements.