[AT] 39 Farmall A coming along.....

[Mark Greer]

No, they had machinists who carefully measured the crankpin diameter and the 
bearing bore with micrometers. If the engine didn't have insert bearings 
then they re-poured and hand scraped the babbitt bearing liners to fit the 
crankshaft. If it had inserts then most manufacturers offered -.001", 
.-002", etc. bearing inserts to accommodate moderate wear of the crankshaft 
and still give correct oil clearance without re-grinding the crank journals. 
If the crank was too worn then it needed to go off to the machinist for a 
re-grind at .005" or .010" undersize and new bearings in those same 
undersizes were used. If a bearing journal was really trashed then you could 
usually grind a journal .020" or .030" undersize and still get bearings to 
fit. The invention of Plastigage allowed the average person who doesn't 
possess expensive measuring tools to check bearing clearances in their 
home/farm shop and not have to drag the engine to the machinist. Of course 
there have always been half-assed repairs used by people to "get by" but 
they are always a compromise and don't last like a job done correctly. It is 
generally more expensive in the long run to "fix" something the wrong way 
than it is to do it right the first time. You will find a lot of these 
"patch" jobs on equipment at consignment auctions. They are "fixed" to work 
long enough to get them through the auction and then.....Fixing the second 
failure is usually very expensive and sometimes costs more than the machine 
is worth. It falls into the same category as buying a cheap tool 2 or 3 
times (because it fails) when you could have spent more the first time and 
owned the good tool for a lifetime. My Dad always taught us that the most 
expensive tool you can own is the one that cost you less to start with and 
failed when you needed it most. The cheapest one is the best one you can buy 
(maybe also the most expensive one) that serves you well for a lifetime.
Mark
Celebrating the Second Amendment one fine firearm at a time.

----- Original Message ----- 
From: "Paul Waugh" <pwaugh at embarqmail.com>
To: "Antique tractor email discussion group" <at at lists.antique-tractor.com>
Sent: Wednesday, March 10, 2010 10:22 PM
Subject: Re: [AT] 39 Farmall A coming along.....


> Did they have this plastigage back in 1939???  What did the original 
> repairs
> call for?? Sounds like overkill. Isn't this when people used belts from
> their pants, for bearing to get by??  I am too old:))
> my 2 cents.
> paul=46555