main bearings

[Soylent_Green]

What is the practical difference between 1/2 , 3/4, and full groove bearings?

[abdywgn]

1/2 groove main bearing is std. auto bearing;there is a groove in the bearing half that fits in the block.Full groove bearing has the same groove in the lower half that snaps into the cap.(usually w/o the oiling hole unless you've bought 2 regular sets to make a full-groove set).3/4 groove is somewhere in between and I think that it's a fairly new addition....but i could be mistaken,maybe it's been around for years.Hope this helps,Bob

[Soylent_Green]

I'm sorry, I should have been more specific; I was wondering the specific gains of choosing one over another. I have been looking for an answer, and have found only that the full groove bearings were good for high rpms because they will allow a better passage for more oil to flow to the bearing surface at high rpms. If this is true, I would think that the only reason to run 1/2 groove bearings is to keep oil pressure up at low rpms. Is this correct?

[jeep_man_401]

I believe some people say that the 1/2 grove will support more load...no since the crank rides on the oil wedge and not the bearing itself...whether it's proven FACT or not is up to the builder. There is more bearing surface to form a wedge so I went on that theory and employed 1/2 grove bearings on my motor for the tractor pulls as RPM is limited to 5800, but very heavy loads.

Unless a guy is going to race all the time I would stay with the "stock style" bearings and upgrade the brand and metals used in the construction of them.

[82Waggy]

The groove is there to supply oil to the rod bearing feed path. Theory is that the full groove provides oil to the rod bearing a full 360 degrees of crank rotation. 1/2 groove only supplies oil to the rod bearing through 180 degrees of rotation.