.0025-.0032 is the spec for those pistons why would .003 be an issue its in spec.  By the op's measurement the clearance now is at.0022  what's the D*** in a bucket about he's got a thousandth to play with still?
I said around .003 thinking after a hone and rounding numbers  in my head still more likely to end up under that anyway.
Don't want to see the op shy away from doing this. I would recommend a machine shop confirm the measurements but by the op's numbers he's good to go all around +.060 rings hone and put it together for many more miles of mini enjoyment.


Jeff

More like a prick in a shirtsleeve........

It might work, but the piston slap would be like a D*** in a bucket.

2.837-2.778=.059 close enough to use +.060 rings by your measurements. With around .003 piston clearance that'll work. Those are AE pistons by the number.

Jeff

WHY are we even discussing rings for a +.060 piston ?

You'd have to chop massive amounts off each one to get it to fit with the correct ring gap, and end up with effectively oval rings.

72mm is a perfectly valid size, as the Australians work in French numbers - 72, 72.5, 73, 73.5mm. 

68mm 998/1098 pistons anyone ?

The piston measures 72mm.

The bore is undersized for +.060" by at least .003" (.006" when piston to bore clearance is accounted for).

There is a running clearance of  .022" for a 72mm piston...

A plug for Hastings...I was looking for a new set of rings for my +20 "S" pistons going in to the 1293 build....none of the UK suppliers had any ideas...not in the parts references they were looking at.

Well, they are Cooper S pistons part no. 19320, needed the narrow rings...and Hastings in the good old USA had them available.

Hastings Manufacturing Company, Hastings, Michigan.

If your pistons are truly flat-tops, they are a "race" piston, as your compression ratio will exceed 12:1.  My best guess is that you have piston C-AJJ3382-60, and we can get rings for that!  This link shows them available in .020 and .040 over, but we do show .060 as well....

//www.minimania.com/part/C-AJJ3382-P/Classic-Austin-And-Morris-Mini-1275-Flat-Top-Pistons

Measure your ring thickness, also what size crank pin .625 or .750? Mixing later cranks with pre A+ blocks require special thrust washers. I recently re ringed a block and found the pistons I removed had 1/16 rings and the better pistons from another I wanted to use were 1.5mm. I think you will be ok on the .060 rings if you get correct thickness. What chamber vol. do you have and how far down the bore were they running. If compression is to high could be running rich and not enough advance to avoid burning a piston. Steve (CTR)

.060 is close but if your measurements are accurate it's not actually +60 is it? You could buy a set of +60pistons and hone to size? You mention a heavy build up of carbon which could be sign of oil being sucked up past the rings. You really need to take the block to a machine shop and have the bores measured accurately for size and ovality then make your decision.

The other three pistons are heavily covered in carbon.  They will be cleaned this week and I will report back if a number is visible.  Does the .060 oversize rings sound ok in theory?  Thanks for the help.

JE makes a 72mm piston but they are for race use so unlikely to be used in a road engine due to cost

The number will usually be around the outside of the crown may be very faint 

Thanks for the reply.  The number 4 is stamped dead center on the crown of the piston.  On the inside of the piston 18013 is in the casting.  I was not able to find a reference to that number.  Not sure where to go from here.  

The pistons should have a part number and size etched into the crown? you need to identify what pistons you have as not all rings are the same between manufacturers 

I have a 1972 mini 1000 with a 1275 pre-plus dual carb.  I have the engine apart and it looks good.  Lots of carbon but the head is straight, the cylinders are clear without a ridge.  It is time to order bearings and rings.  The bearings are easy with numbers stamped on the back. They id as 2145 (010) and 5146 (010) so it looks like the crank was turned .010 all good.  The question is what rings to get.  The bore measures at a large 2.837in (72.06mm).  I suspect the bore will increase slightly with a light honing. The pistons are flat top 3 ring and measure at the joint 2.8348 (72.00mm) so .0022 clearance.  Since the bore measures .0575 over the spec of 2.778 inches my best guess is to order rings at +.060.  Am I on the right track?   Want to talk crank end float as well?  I am sitting at .011in. Too big but the STD thrusts measure .088 so I think they are worn and a new pair of STD thrusts will put me back in spec.  

Thanks in advance for the help.  Mike.