22-03-2021, 09:18 AM
With such a satisfying time consuming hobby who needs the internet or TV? The difficulty is to avoid chatter marks. Plastigauge is only reliable when newish. It dries hard. it recently dawned that after a myriad tightenings over the decades during refitting sessions the conrod bolts on my car must be near their fatigue limit! Most older books recommended a larger contact area than acheived there, although a thin layer of blue can be very thin.
For car bearings a slight full or near full width clearance increase at the parting line is now general practice.
Scrapers can be made from old files but must not get hot when grinding.
To the 1940s at least on cars without filters it was considered good practice on major overhaul to tighten the caps and relieve with a generous scraping. This removed the hard dirt embedded layer and gave a low wear arte bearing material as new. The surface of old bearings is like a snail shell and hard to scrape. When heavily scraping rods easy to alter the alignment.
it was common to fit to just nil clearance but this now considered dubious practice in car engines..
For car bearings a slight full or near full width clearance increase at the parting line is now general practice.
Scrapers can be made from old files but must not get hot when grinding.
To the 1940s at least on cars without filters it was considered good practice on major overhaul to tighten the caps and relieve with a generous scraping. This removed the hard dirt embedded layer and gave a low wear arte bearing material as new. The surface of old bearings is like a snail shell and hard to scrape. When heavily scraping rods easy to alter the alignment.
it was common to fit to just nil clearance but this now considered dubious practice in car engines..