3.0 main bearing oil mods.

[Ondonti]

Had these ideas as I was assembling a shortblock last night with some weird near free closeout sale bearings from rock auto. (only $15 for my rod bearings and only $12 for my mains). Thought they were going to be Clevites but oh well.

I feel.....everyone I see posting on 3/S sights obsess about the main oil passages or other oil passages (to the heads) hogging oil because they are simply "near each other". I do not see these as real issues and feel that the level of inane obsessiveness people put into balancing intake manifolds would be better served in an oil system that actually requires a constant flow (not a pretend constant flow from valves that spend most of their time closed) and where you can't compensate by modifying your tune. These wasteful "big carburator on junk motor" ideas probably come from knowledge of bad oil passages on other motors (like old Chevys).

The 6g72 Lubrication system needs balance more then anything else. This is an easy way to do that without losing a bunch of bearing surface on the lower bearing.








I just made up the number of holes and the locations as an example. These bearings are weird in that they have a smaller groove on the lower bearing, a useless set of holes, and a larger flowpath in the upper bearing compared to OEM. These are non oil squirter bearings that are no longer made new by companies like Clevite.

Motor I just put together has no use for bearing improvements but my Duster might need them if I start pushing the cast crank hard again.

[Vigo]

So i'm guessing it is an established thing that the bearing without the groove shows more wear?

[Ondonti]

So i'm guessing it is an established thing that the bearing without the groove shows more wear?

6g72 main bearings are grooved top and only the top edges of the bottom bearing. I have never seen anyone do anything except slap in off the shelf bearings (which are now available coated etc).

What I could say is that the crankshaft flexes and center mains suffer at high power levels. Since 6g72s have rod oil squirters the oil film will be weaker on the center mains since there is more "outlet" then "inlet" for oil flow compared to the outer mains.

[Shadow24]

Are you talking ALL 6G72s or just the 12v? I know there is a crank difference between the 12v (cast) and 24v (forged), so wouldn't that have a significant impanc on whether or not the crank flexes?

Also, af $15, why not get 2 sets of bearings and use only the grooved halves?

[Ondonti]

Are you talking ALL 6G72s or just the 12v? I know there is a crank difference between the 12v (cast) and 24v (forged), so wouldn't that have a significant impanc on whether or not the crank flexes?

Also, af $15, why not get 2 sets of bearings and use only the grooved halves?

The idea here is to get oil directly to the bottom without losing a lot of bearing surface. There is reason they don't run it all the way around.
Crank flex is a fact of life when you have 2 rods per center journal and some bad harmonics or some knock.

[Irocelectric93]

So brent are you asking which would be better? Drilling holes in the bearings or cutting a small groove? Or are you suggesting doing both?

[Sundance 6g72]

I used these in my engine. They are king bearings for the DOHC engines. got them from 3SX




So I have the holes just not the groove?