22-03-2021, 08:26 AM
I just came across this old film about bearing scraping:
I recently had to buy a set of scrapers to relieve the corner of one of the main Babbit bearings in my Riley engine. The new crank has more of a radius on the journal so needed to chamfer the corner of the bearing a little more. That was easy enough but it is interesting that the set of scrapers I bought were just like the ones shown in this film. Is this the standard set for scrapers? A lot of old manuals/articles talk about scraping but I have not actually seen a good description of the process as shown in this film. I was just wondering how good a demonstration this is?
The crank and rods I am using in the Riley engine (Arrows) are more modern design and use shells (so I will run an oil filter) so I don't actually need to scrape anything this time round but it looks like a useful skill to have. I always wonder though in modern engines with shells they always say check the clearances with plastigauge but then never say what the hell you're meant to do if it is wrong! With a new precision machined crank and modern precision shells what are you supposed to do if the clearance isn't right? Send the crank or rods back and complain?
Simon
I recently had to buy a set of scrapers to relieve the corner of one of the main Babbit bearings in my Riley engine. The new crank has more of a radius on the journal so needed to chamfer the corner of the bearing a little more. That was easy enough but it is interesting that the set of scrapers I bought were just like the ones shown in this film. Is this the standard set for scrapers? A lot of old manuals/articles talk about scraping but I have not actually seen a good description of the process as shown in this film. I was just wondering how good a demonstration this is?
The crank and rods I am using in the Riley engine (Arrows) are more modern design and use shells (so I will run an oil filter) so I don't actually need to scrape anything this time round but it looks like a useful skill to have. I always wonder though in modern engines with shells they always say check the clearances with plastigauge but then never say what the hell you're meant to do if it is wrong! With a new precision machined crank and modern precision shells what are you supposed to do if the clearance isn't right? Send the crank or rods back and complain?
Simon