Unusual Piston Knurling Tool

Tom Wesenberg

Tom Wesenberg

Well-known member
Last summer a guy gave me this tool. When I looked at it I had no idea what it was, until he told me it was a piston knurler. It reads:
SEALED POWER CORPORATION
PAT.PEND.
And on the top side near the handle it reads:
HKSCo
Newport, KY.

Notice it has a wingnut to adjust the tension on the rollers. The bottom roller in the picture has a sharp edge, like a tubing cutter, and the top roller has a 1/4" wide by 5/8" diameter roller. I assume you turn the engine until the piston is down as far as it will go in the cylinder, then run this tool up and down the exposed part of the piston skirt. I'm not sure of this however, as I've never seen or heard of a piston knuler like this before. Does anyone know for sure how to use it?:confused: Thanks
 

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nope. only thought you could knurl them out of the block. and then only on the thrust side, not all the way around like this looks...
interesting tool...
 
Saw this on the web,

"Sealed Power brand "piston shirt stretcher". It looks to be from the 1930's. The instructions say to tighten the tool on the minor thrust side of the piston, then pull it down the skirt. It is built like a tiny english wheel, with a flat wheel on the outside and a "V' shaped wheel on the inside... Each pass of the wheel is supposed to expand the skirt .001..... "

This looks close;

http://www.google.com/patents/US2289941

and

http://www.google.com/patents/US2341959
 
When I was about 19, there was a lot of them at swap meet tables.

A lot of times it depends on where they are made, and where they were distributed in what areas of the country.
 
Thanks Mike for finding the patent application on the tool. And thank's to Ray for emailing me the original directions. Looks like I should have called the tool a "RESIZER" rather than a "KNURLER".
 

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years ago, 40's 50's it was excepetable and common practice to expand pistons or kneral the skirts of pistons to restore piston to wall clearance on slightly worn pistons during an overhaul. the tool looks to be older or about the 30's 40's
 
Piston cylinders that have a larger clearance for the piston can make a noise until the piston and cylinder expand.

But if the rods are out of alignment, and 100 % are if they haven't been checked for twist, bend, and off set, that is the true and only piston slap, because the piston is always cocked in the cylinder.

A piston that is not cocked in the cylinder rides straight up and down in the cylinder and floats in the rings, with no premature wear.
 

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On the old full skirted cast pistons, in was common to have a collasped skirt. pistons back then were ground round with expansion slots in the skirt, after use the piston skirt would collaspe from the trust of the connecting rod. today they are cam ground (ovel) to allow for closer piston to wall clearance, expansion rates are greatly improved, and when at operating temperature the are round. modern piston alloys, skirt design, and teflon skirt coatings allow for closer fitting clearances today. Yes a bent connecting rod or misalignment will put a thrust on a piston. as noted by the wear pattern on the skirt.
But back then that was a proper fix. worn or new rings do not hold the piston square to the wall, they compress.sealed power/perfect circle Dr of motors.
 
Last edited:
1930 coupe said:
Most people do not realize how easy it is to bend a rod. You can take a rebuilt rod out of a box and put the small end in a vice and remove the nuts on the big end with a wrench. If the nuts were tight the rod will bend when you pull on the wrench. You cannot put it back by eyeballing it you can only get straight if you have a special tester to check it.
Click to expand...

100 % Right!
 
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