Isuzu G-series Twin Cam

I've just pulled the pistons out of the G180. They were in there pretty tight, partially due to some rust which had, over time, washed into the bores from, I'm assuming, the valves.

Anyway, I've never had a close look at pistons or piston rings before. Are they supposed to be able to rotate!? My understanding is they must be rotated to a certain angle, and (I'd assume) fixed there somehow? A few of the piston rings revolve freely, and spring out a little when the cylinders leave the bores. Is this normal or are the f**ked? I should probably get new ones anyway, but they do look new and shiney .

There's a bit of rust which has washed, from above, past the two upper rings, on one of the pistons... This seems to tell me it isn't making a particularly great seal? I'm just an amateur when it comes to piston rings, so any tips would be great.

On a sidenote, I found that a great way of getting the pistons out, when they're really tightly in and in an awkward position, is to line everything up really straight, get a really HUGE flathead screwdriver or similar (the sort which are about 45cm long), with a big plastic handle, put the handle onto the inside of the bearing that joins the cylinder to the crank (bottom of piston arm, basically) and tap the metal end of the screwdriver very lightly with a hammer.

ok
i assume u r meaning pistons when u say cylinders

and spring out a little when the cylinders leave the bores.

You should be able to rotate the rings when they r on your piston there is no way of locking them in they just line the gaps up roughly on opposite sides of the piston so the gaps arnt in a straight line and thats it ,but as u said if they have been sitting in a motor not doing anything and there was some condensation in the chambers they may have rusted away then thay r buggerd. When u r rebuilding a motor anyway the least u do is change the rings so it doesnt really matter if they r buggered. However if this is the case then check that it has not eaten into the cylinder wall at all i have pulled down a couple of motors that have had this problem and the block was rooted. Hope i have shed some light on it 4 ya dude

Yeah, I meant pistons, I always end up writing someting totally unrelated to what I'm thinking.

Thanks for the info, the bores look sweet as though . When I stop spending money on shit like springs and speakers, I'll take a piston into O.G. Speed Shop and have them make me up a new set. I just wanted to double check before I did anything, as this is the first time I've pulled apart an engine, and I'm doing it alone on the floor of my spare room...

I think standard G series rings will suit. perhaps one of the other members can verify that.

Just be sure to only buy standard type (plain cast iron) rings to quickly bed and seal as well as minimising bore wear.

Never use chrome-moly rings because they will wear the bore sooner and don't really offer any advantage over plain or moly rings. If you plan on having replacement liners pressed in then chrome-moly might be fine providing the liners are of a fairly hard material.

In a few weeks I will take the rings into O.G. Speed Shop and have them looked at and measured up, and then check them with standard G180Z rings, then post it up on here.

Is there anything I should know about re-seating them? Besides that the gaps should be on opposite sides of the piston?