Quote:
Originally Posted by tom s
JMHO,I love the Butlers,buy quite of bit from them.BUT from the email from them they knew there could be a issue and for sure there should of been something put in with the receipt to call attention to the issue.And I still have not found a narrow main bearing?H are for HiPo and X is for 1 thou more clearance but find nothing with a N like a narrow rod bearing?Tom
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As stated, I am not an expert on engine building and am sure you have more experience than myself, but I found a few interesting things in an article on the web. I realize that rod bearings come in narrow widths - which is more of what I was leaning to. The chamfers on the main bearings I did find available for a small block. I also know that you can purchase a tool to chamfer bearings, but of course the average guy with an electric drill and vice isn't going to be doing this.
Clevite & King sell a .001 narrowed main bearing set (also .002 for Clevite) and King main bearings do advertise the chamfers for large radius cranks.
Here is what I read: "Taken as a generalized statement, stock replacement rod bearings are often slightly wider than their high performance bearing cousins. To illustrate this point, we measured the width of a set of stock replacement aluminum Federal-Mogul connecting rod bearings for a big-block Chevy compared to a set of Federal-Mogul (Speed-Pro) performance tri-metal bearings. The stock aluminum versions measured 0.885-inch while the performance bearings were 0.020-inch narrower at 0.865-inch. Using the wider bearings on a performance forged steel crankshaft could cause the outer edges of the bearing to bind on the larger fillet radius of the crankshaft. This could cause immediate bearing failure, and at the minimum will cause bearing debris to be released into the oil."
Now I found this interesting and thinking out of the box, is it possible the bearing halves were mixed up at the factory? I realize you align the oil hole in the bearing half with the oil hole in the block, but what if the wrong half got drilled at the factory? Why I ask is that this same article mentions the register tang position having an upper & lower position to the bearing half - this is again in regards to a rod bearing, but could this apply to a main?
"Narrowed bearings also brings up the issue of rod bearing chamfers. Most performance rod bearings are designed with a chamfer on one side of the bearing to accommodate the large radius on the edge of the journal. Since the inboard side of the bearing avoids this fillet radius, there is no need for a chamfer on both side of the bearing. But with both upper and lower bearings, this demands that the bearing be placed in their proper orientation.
Because the bearing is located by its tang, a chamfered bearing must be installed either as an upper or lower bearings since the chamfer will be on the opposite side for a lower compared to an upper bearing half.
This requires performance rod bearings with these chamfers to be marked “upper” and “lower”. Some bearing companies abbreviate this by using “U” and “L” as stamped on the back side of the rod. If these bearing halves are incorrectly installed, the bearing’s flat edge will face the fillet radius and create immediate bearing wear in this location–often the rod will even bind once the cap is torqued. "
I read that the bearing tang was slightly off. Is it possible the factory.manufacturing source had the bearings flipped and drilled the oiling hole in the wrong bearing half thus positioning the tang in the wrong place and pushing the bearing in the direction of the crank radius rather than away from it? Just thinking here knowing how quality control can be - especially if outsourced from overseas.