Brand new main bearing nicked. Usable?

nm9stheham said
Yep, from their documents, they believe it is the way to go. I've found test and research articles supporting the use of a full lower, and it is actually more justified the more the engine is powered up.

BUT, like so many things in this world, it all has to be conditioned on other factors specific to the engine.... the limits in oiling the SBM rods at high RPM are a known thing. Where that 'high RPM' range starts, I really can't say.

The limit starts with the viscosity of the oil and the temperature of it. It also calls into issue the diameter of the journal as in with big block Fords, a massive bearing will fail very soon at high rpms because oil no matter how thin or thick, the oil can only travel to a certain speed, beyond that is sheer point which is where the bearing overheats and fails. The same factor affects pistons and cylinder walls. There are formulas and even charts that give limits so you can calculate all of these factors when you are bench racing. Strokes , rod lengths, bore offsets, pin offsets, all kinds of things to work with here. Journal sizes, clearances affect it too. Look at an Indy engine, with a tiny main journal and rod journal with a really short stroke and a bore that is massive when it come to bore to stroke ratio. You would wonder how it even stays together with such large side clearances and things like piston guided connecting rods. Those engine run such tight oil clearances they have to preheat the engine and oil before they will even turn over to start without trashing the bottom end. Going back to the SBM engine there are so very few old 340's and even the other engines left around the were run as race engine simply because the front main split all the way up to the cam because of the oil passages drilled there. not just one but three. Too much casting was taken out for necessary lubrication, which could have and should have been done differently in this design with relocated feeds like in the center or rear of the block. GM went through this with their Gen IV, V, VI and then the VII's winding up with what they cal priority mains oiling system. The only thing I found with these in the later years is the size of the holes was reduced to the point that in many engine blocks like the later 454 and medium duty tall deck 427's the factory actually had miscalibrated drilling processes in the factory and the intersections from the main oil gallery to the passages to the mains missed and the engines had mulitple crank and bearing failures !!! I recently completed a rebuild of one engine that suffered from this where another shop, make that the first shop that attempted to repair this engine and even a machine shop that did and redid this engine and failed to find this problem. At various time with this engine full groove mains were installed which aggrevated the problem, a high volume high pressure pump was tried and even an oil cooler delete was tried, the only fix was to re drill the oil feeds. Bottom line when building an engine for anything beyond what the factory did, such as what most of us do, is to check EVERYTHING, oil passages, clearaces and as I said in other post, I will never go with another set of Full Grooves, I had cross drilled cranks, modified half groove bearings, I have even drilled out the holes in the upper main inserts to match the hole I drilled in the blocks to insure that more oil CAN get to the Mains and Rods. NO engine ever made at a factory isn't capable of giving more then what the factory gives you if you pay it to do so! The only limit is how much can the block and other parts take before something starts to say that is all like splitting or just blowing up like when a rod bolt fails, which in more case than not is a result of lack of oil to it.