When doing an insert conversion you have to also get pressurized oil to the rod journals, since splash oiling cannot provide adequate oiling for a bearing. How are you going to do that?
The use of insert bearings with the jet oiled system has been a rebuild option for quite sometime now - for practical reasons. There are very few places that pour babbitt anymore.
When setup correctly the jet oil system is good for around 15 psi at the rods. This limits the RPM and C/R in a jet oiled engine. But the thickness of the babbitt linings is also a factor.
Roger Huntington discussed early mods to babbitt rods in his book. The shops would first pour brass as a 'shim' and then pour a thinner babbit lining. This allowed for higher C/R loadings that would have distorted the normal stock spec babbitt linings.
I am following Huntingtons specifications for jet oiled clearances but with insert bearings.
