22-03-2021, 12:07 PM
I hand scraped a set of 10 thou undersize big ends to fit a new Phoenix crankshaft. I could not find anyone at the time willing to bore the old metal; they all insisted on remetalling. Not wanting to get involved with that much time and money I decided I had nothing to lose. I had scraped larger 6" bearings for machines when I was at GEC Witton, so the technique had to be similar but on a smaller scale. Not having any scrapers I sharpened the back of an old hacksaw blade; holding it slightly curved it works fine. By tightening the bigend so that it would just turn on the dry shaft a couple of turns will mark the white metal on the high spots. A gentle scrape will leave a situation where retightening will show other high spots. When you have repeated the process enough you get to a point where things are right for reassembly. Patience is essential, and four rods took nearly 8 hours, but after more than 20,000 hard driven miles the bearings were still good on dismantling for a different problem.