[b-man]

I have built several street engines and I have always installed the bearings right out of the box. I even have a mild 455 bracket race engine (400 HP, 8.6:1 comp, shifted at 5200, 5700 max RPM) that still has the all of the original factory bearing intact, it runs fine.

I know many builders will open up the oil feed hole on the upper main bearing half to match the size of the feed hole in the main saddles. Others go even further and add an additional hole right next to the original feed hole (or slot the original hole to accomplish the same) to match the gallery that actually sends the main bearing oil from the cam bearings.

I have read about some builders who modify the thrust for improved bearing life, I'm very interested in the best way to do this. A lot of us street runners and racers with auto trans cars have higher stall converters, those with manual transmissions run stiffer pressure plates to help couple the power. This puts more load and stress on the thrust bearing.

Users of auto and manual trans cars on both the street and the track would understandably like to keep their thrust bearings in good shape for the long haul. Modifications to the bearing where the two halves meet have been mentioned several times, a 'V-ing' of the parting surfaces to let more oil to the thrust surface has been one but I'm unclear on the actual looks of this mod.

What are the best mods that can be done to the main bearings, especially the thrust bearing to add addtional lubrication and load carrying ability? I know some of the pro builders that contribute tech help on this site each have their own tricks. It would be great to be able to see pics of what kind of bearing mods are being done by some of the better builders to add longevity.

Any input on this subject would be greatly appreciated by many members on this board.

I'll be posting this thread in the both the Street and Race sections for more coverage. Thanks again.

[Formulas]

I take a small jewlers file and put a bevel where the bearing halves mate on the aft side of the oil groove on the face of the bearing... this provides a positive pressure path to the aft and most important part of the thrust bearing.
Plus i have my converter feed in the trans pump restricted..

[WARIARGTO]

Best thing is to just buy the FM race series main bearings.
http://www.federal-mogul.com/cda/con...3_6815,00.html
Talk to Bill Takanabe. The thrust on those is just what you're looking for. If you want to do it yourself, I'll try to attach a pic that was posted on these forums a while back I think by OMT.

[PONTIAC DUDE]

Yes. the above pic is what I recommend and have been doing for over 2/3 years. NASCAR development used first by Ford.
That's one of the bearings I either modified or recommended to do for OMT. Been to long and CRS . LOL.
I don't recommend opening up the hole the same size as the feed hole in the block. Just elongate it 3/4 the size of the original bearing hole towards the angled feed part in the block. The FM 400 race mains are slotted already and haven't seen an issue with them. But have had to drill the slot wider for #1 in some blocks in the bearing as the block holes aren't located in the center of the main journal of the block. Be careful with #1 and modifying bearings as hydraulic cams and the lifters feed off this journal and don't want to rob the oil supply to much to feed that side. Lifter Oil Restricted engines aren't an issue.

[b-man]

Thanks a lot guys, exactly the info I was looking for.