engine rebuild piston rings size?

[ChainsawMonkey]

Hello all
I have been rebuilding the engine from our 3.7l 2002 jeep liberty sport.
I just honed the cyls and I assumed I could just put in standard piston rings.
Well I desided to measure first. Not having the correct tool I desided to check the ring gap with the old rings. Well the the upper is out on every cyl. 0.65mm 0.58mm 0.60mm 0.63mm 0.58mm and another 0.58mm.
Spec being 0.23-0.39mm with a wear limit of 0.43mm
So do I assume this is from wear and order new standard rings or go a size up? What size would you recommend?


Cyl walls are coming in at 24.720in 24.675in 24.745in 24.685in 24.705in
Intermediate rings all came back good. 2 at 0.55mm 4 at 0.53mm spec is 0.40-0.66mm with a wear limit of 0.74mm. Which has me completely confused. Why are the uppers so off when the Intermediates are right on?

 

[Road_Runna]

2024 and just seen your post.
I'm doing a rebuild on mine, and measured about .030" thou of an inch on the old rings.
I checked gap on my new rings (standard bore of 3.66" of an inch) I honed it with 230 and finished with 320 grit and I'm sitting at .013 on an inch on my top rings, and .0165 on my secondary rings.
I noticed Jeep used chamfered top rings from the manufacturer, which break off easy.

Did you use a diabore to check diameter of the piston bores? A dial caliper would give you that many inconsistent readings like those you mentioned.

 

[KJowner]

If you have worn bores then a hone isn't going to fix them, as you have discovered they don't wear round and a hone just follows the wear and makes matters worse by increasing the clearance.
How slack are the pistons in the bores?