Piston Expanders?

The instruction sheet is interesting as well! Perfect Circle no less.
 

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Lot´s of ways to "fix" things if labor was cheap.
Grinding pistons to undersize and reusing.
Piston ring regroover and steel shims.
 
I had pistons expanded by shot blasting back in the 70/s.

Was a normal everyday job then.
 
You can´t get material worn away back again so what you get after knurling is a piston with less lifespan then a new one.
Back when labour was cheap and lack of parts was an issue i can get "fixing" stuff.
 
flatheadmurre said:
You can´t get material worn away back again so what you get after knurling is a piston with less lifespan then a new one.
Back when labour was cheap and lack of parts was an issue i can get "fixing" stuff.
Click to expand...
Sure, when an engine is rebuilt new pistons are used but when it is overhauled, knurling the piston extends it's lifespan, at a lesser cost. Call it the cheapest way but that's what people wanted, and it worked.
 
Perfect Circle had a knurling attachment for the lathe to knurl the skirts that would work for a while but today the hot setup is have the skirts coated by Swain Tech .
They can build up the skirts a couple of thousands.


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I had a '70 Triumph 500 in the early 80's that had knurled pistons. I took it apart for other reasons, but it ran fine. First time I had seen them.....Mark
 
There were lots of ways to do the cheapest possible service on an engine - to get it back on the road and in the process, spending the least amount of dollars. Dang near every small town had somebody who "rebuilt engines" . . . everything from lawn mowers, to tractors, to cars. People didn't have money to spend and there was a lot of cheap labor available (young 'blue collar' folks) - without XBoxes, Computer Games and Texting to distract that 'cheap labor'. LOL
 
I had a set of original Mopar piston expanders just like these for my 50 Plymouth but I didn't use them when I had the engine apart because the pistons still checked out very close to factory specs.
 
I have heard of knurling a piston to decrease the slop but these things I have never seen. So if I read it correctly, they actually expanded the piston, did these thing really work?
 
I also knew about knurling, and have seen the little tooling parts for it. Then it looks like there was a setup for expanding pistons before you put them in. But these deals are a whole new idea for me.
 
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