Main bearings 1/2 groove or 3/4 groove

That is all a personal decision ...
A full groove will help a deficiency in the rod bearing / journal union to be better but, a half groove, (actually 165 degree groove which nobody makes), will help the load carrying capability of the main bearing oil film.

A 3/4 groove was an attempt to get the best of both worlds. So, it really depends upon the actual working atmosphere of all the bearings and where you think needs the biggest "helping hand"..

Dave De wrote:

rmcomprandy wrote:That is all a personal decision ...
A full groove will help a deficiency in the rod bearing / journal union to be better but, a half groove, (actually 165 degree groove which nobody makes), will help the load carrying capability of the main bearing oil film.

A 3/4 groove was an attempt to get the best of both worlds. So, it really depends upon the actual working atmosphere of all the bearings and where you think needs the biggest "helping hand"..

Aren't 385 series engines more prone to rod bearing failure over main bearing? This would give the 3/4 groove more application? I am basing that on a failure of mine years ago with a D9 block. Now A460 block with priority main may not be an issue for me. Maybe this is a non-issue to get oil to the rod bearings 50% more time duration?

The quality and strength of the parts, (including oil thickness and clearances), used in a rotating assembly will change the point of the "weak link" and what will be best for THAT situation.

The only way to actually know is to run it within the environment it will get used, take it apart and inspect the condition of everything and re-assemble it all accordingly.