Swaping pistons

[nasaman]

I acquired a VY Auto Equip 2003 commodore ecotec. The car was in wonderful condition however the motor had been run into the ground. Driven with a leaking head gasket until a couple of pistons suffered damage and one resulted in a hole in the top of the piston. I extracted the motor and have removed the pistons and ran a hone through the bores and they look very good. No damage to the bores themselves. I have another ecotec motor here and it only had 140 thou Ks on it but had been run on sheep dip I think and this resulted in corrosion at the back plate and it is beyond repair by me.
I am now thinking to pull the pistons from the damaged block and put them in the good block that I have honed lightly. I have replaced rings before and I have replaced big end shells before however I have never swapped pistons from one motor to another. So I am wondering if this is a good idea. Is there anything I don’t know that will trip me up. I did try to repair the damaged block and I even completed and installed it into the car before discovering it just wasn’t going to stop leaking so I have pulled it out again and am considering the piston swap to the original block. Of course I would install new rings and big end shells but I am just a little nervous that there may be something I don’t know that would make this a bad idea. I certainly don’t want to install the motor again just to discover piston slap or something that would make me pull it out again. Heaven forbid. Can anyone give me any ideas. I am not far from Cairns and it is hard to get a reasonably young ecotec here or they want an arm and a leg for it. There are some good priced motors on EBay but the transport kills it. I noticed that even a motor with 140 Thou Ks the pistons seem a good fit until you extract and de ring then they seem a sloppy fit anyway.
Do you think I would get away with a complete piston set swap.

 

[Brettly-2008]

Getting piston/cylinder clearance correct is an important part of a rebuild. But if these pistons are original virgin bore size and the new motor is the same, there's no reason it wont work. I don't really see a problem but it probably won't build cylinder pressure as well as a rebuilt or new engine. But if it's just a regular daily who cares?

 

[EYY]

Rebuilding these things at home is pretty much a no go. The rods need to be resized correctly as they'll be ovalled currently - new bearings won't sit in the rod and cap properly and won't have the right clearance for the crank. The cranks don't like being ground either, and if they are, they need to be index ground to avoid cracking in the future.

Pretty much all of the bolts are TTY which means that they need to be replaced every time they're used. The ring seal/piston tolerances are the least of your problems in this case.

The best approach is to purchase an engine from a wreckers with warranty (under $200 - even cheaper than a set of pistons alone), and if you're concerned throw some head gaskets and inlet gaskets at it and get another 150,000km+ out of the car. These engines are very robust, and it's rare that something happens to the bottom end.