Quote:
Originally Posted by Gene F
Cracks, the cylinder bores, and or the crank journals too small....these are the real things that jump up and bite a person on rebuilds.
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Something that often is overlooked in this is this hobby has seen a 180° degree turn in the mindset of restoration in the last few decades where now hobbyists just want to replace and/or modify rather than restore. Items such as 'numbers matching' (which was once a big thing) or trying to restore a car as authentically as possible seemingly has changed where some hobbyists do not understand that 'restoring' still has favor by some hobbyists. Technology today makes restoring older engines even more possible. If something is jumping up and biting the person during a rebuild, then generally speaking, the machinist did not clean, wet & dry magnaflux, pressure test, and sonic test the components during the evaluation portion PRIOR to beginning the machining processes.
Quote:
Originally Posted by BrianH
Making the larger main bearing caps is yes expensive time consuming. The real work is machining the block to match. Solution is grinding the "B" crank main bearings to "A" crank size and go from there. I have one in my latest engine build and is working fine.
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Brian, the only thing I will caution you on about grinding the journals from 2.000" to 1.625" is when you remove 3/16th of an inch off of each side of the journal pin, you are well below the heat treated portion of the pin which makes the surface very soft. Often times the reason why this was never much of a problem was if the rebuilder used a softer alloy of Babbitt to support the journals. Therefore, if someone wants longevity either with correct Babbitt composition, -or with insert bearings, then the crankshaft really needs to be Nitrided which will give about a 0.030" surface hardness.