.015 over pistons

oldwoodsman

oldwoodsman

Senior Member
Having pulled these pistons from a motor I'm working on I was wondering if .015 over is a common size for an overbore. Does anybody have any info on the maker of these pistons? Just curious.
Thanks Tim
 

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The manufacturer could have been any one of many manufacturers during the post Model-A era. It could as well have been turned down to 0.015 on a lathe by the thousand odd machine shops during the same era that routinely turned down "semi finished" pistons to fit a cylinder of any size to which the hole was cut.
 
oldwoodsman,

Those look like replacement Ford Pistons, they show them in the Part List, the giveaway is the Script Arrow for orientation.

They are later style as the original Model A and B pistons had a center one piece lock between the Rod bushings, and not the clips at the ends of the pin.

Above the pin, opposite the side shown show have a Ford script.

Darryl in Fairbanks
 
They look like Ford replacement stock from the "F" on that Front designation.

Joe K
Edit: Beat me by less than a minute.
 
I need a closer picture, but it also looks like the bottom ring has a spacer installed. Are you going to bore this for the next oversize?
 
I have heard of oversize, "oversizeed pistons. I would like to find a set of .130 oversize if they're available. Cheaper than a bore and sleeve job !
Terry
 
After 60 years working on engines this is the first time I've seen any one put a oil ring in the middle. People never stop surprising me. Tom that is a spacer in the bottom groove.
 
Tom Wesenberg said:
Looks like someone installed the oil ring in the middle slot instead of the bottom slot.
Click to expand...

Tom which is the oil ring?

darrylkmc said:
oldwoodsman,

Those look like replacement Ford Pistons, they show them in the Part List, the giveaway is the Script Arrow for orientation.

They are later style as the original Model A and B pistons had a center one piece lock between the Rod bushings, and not the clips at the ends of the pin.

Above the pin, opposite the side shown show have a Ford script.

Darryl in Fairbanks
Click to expand...

That was my thought on the arrow Darryl, but no ford script anywhere on the piston

Tom Wesenberg said:
I need a closer picture, but it also looks like the bottom ring has a spacer installed. Are you going to bore this for the next oversize?
Click to expand...

Tom The bottom ring is made up of three pieces a narrow ring on top and bottom and a wider ring between that has openings through it. Is this the
oil ring? No I'm not boring it Tom. I had no history on the engine so I took it apart to inspect it so I could use it as a short term replacement while I did some work on the engine that is in the car. I found it had good Babbit and cylinders, but a bad hole for one of the head studs. I have put a pipe plug in the hole and I'm waiting for studs and a tap. Didn't want to put too many $ into it for the time being and until I see how the head stud repair worked out.
Thank you everyone for the input
Tim
 

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It is right the first picture looked like a oil ring in the middle. But it is one of those rings with a grove in the middle like they used to use.
 
OK, now that I see a better picture it does look like the oil ring is the bottom ring, but the middle ring also looks like an oil ring. Maybe it's just a second ring of a design I've never seen before. At any rate, the oil ring should have the gaps widely spaced, and not lined up as pictured.

This last picture also shows some evidence of pinging. Notice the light erosion above the top ring.
 
Tom Wesenberg said:
OK, now that I see a better picture it does look like the oil ring is the bottom ring, but the middle ring also looks like an oil ring. Maybe it's just a second ring of a design I've never seen before. At any rate, the oil ring should have the gaps widely spaced, and not lined up as pictured.

This last picture also shows some evidence of pinging. Notice the light erosion above the top ring.
Click to expand...

Tom all the pistons came out with the three piece bottom rings gaps lined up. When I put it back together I'll space them out. The center ring groove is very shallow and doesn't go through to the piston. Does anything need to be done to the erosion on the pistons as some have a little more evidence of it?
 
What are you doing to the engine?
Notice the wide groove for the top ring, due to wear. If it was my engine, I'd spend the money for new pistons and rings, and have it bored or honed to the next oversize.
 
Tom Wesenberg said:
What are you doing to the engine?
Notice the wide groove for the top ring, due to wear. If it was my engine, I'd spend the money for new pistons and rings, and have it bored or honed to the next oversize.
Click to expand...
Tom As In post #9 I'm planning to use the engine as a temporary replacement in my car while I do some work to it's engine. I think what you see In the picture is a shadow from the top ring. What should be the clearance between the ring and the groove? It is at .005 now.
 
OK, for a temporary engine you'll be OK with .005" ring side clearance, but it only needs 1 or 2 thousandths. Place each oil ring rail a couple inches to the side of the expander gap, and install the pistons with no gaps in a line. I like to place each ring's gap about a third of the way around from each other, and I don't have the top ring gap by the exhaust valve. More heat by the exhaust valve and the ends of the ring could heat up quicker than the rest of the ring, plus less chance of the hot gas blowing through the gap if the gap is away from the valve.
 
Tom Wesenberg said:
OK, now that I see a better picture it does look like the oil ring is the bottom ring, but the middle ring also looks like an oil ring. Maybe it's just a second ring of a design I've never seen before. At any rate, the oil ring should have the gaps widely spaced, and not lined up as pictured.

This last picture also shows some evidence of pinging. Notice the light erosion above the top ring.
Click to expand...
but the middle ring also looks like an oil ring. Maybe it's just a second ring of a design I've never seen before.

They use to use them back in the day. That was before scrap rings. Maybe they though they would seat better with those wide rings.
 
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