So im building a 350 that came out of a 88 k2500 im about to start putting it together but im wondering if i should change the piston rings because the guy said it was burnin oil and it had 180k miles

Id rather just change the rings and not the pistons.

 

I'm assuming the motor is all apart? If it is take the piston out turn it upside down with it still attached to the connecting rod and put it back in the bore make sure it's a good 3-4" in then take a feeler gage and slide it in between the piston skirt and cylinder wall check all around it and make sure your cleanse is good I don't know what they would be for your motor probably around .002-.003 if that's all checked out then go ahead and put your rings on. I'm usually really **** I put the rings in the bore and I match the ring gaps with what the package of the Rings say. Best way to putting the rings in the bore so there square is put the ring in the bore and put the piston in upside down in the bore to ensure the ring is perfectly level then check your gap on the new rings for stock probably somewhere around .016-.018. If there with in spec leave the rings in the bore and do the same on all of the cylinders then take the piston for the bore it came out of and the rings you clearanced for the cylinder and put them on if you had to file any of the Rings make you you debut the ends with a file on a 45. Also when putting rings on make sure te gaps are staggered put some oil on the rings and the wrist pin and install it. Make sure when you install the piston into the bore that the Jornal on the crank is rotated to the bottom so you don't smoke it with the connecting rod.

 

So basically the only way to check is by pulling the pistons out? Looks like im getting new rings haha

 

Well if the motor is all together then check each piston with compression tester if all cylinders are good chances are it's your valve guide seals in the heads that are gone

 

Motors down to the block and i have new (well new to me) vortec heads to go on there only thing in there is pistons but if i could avoid getting new rings thatd be great haha

 

Well since it's down to the block and it has 187xxx miles I'd at least change the rings it's better to do it now then putting it all back together and finding out you should of changed the rings and having to pull it out again. How do the top of the Pistons look?

 

Well i cleaned the carbon off the top and they look fine a couple have some little marks but im not really worried about that

 

I'd still recommend replacing the rings but if you want to just get the car running you can roll the dice and put the heads back on and see if it still burns oil you might get lucky.

 

Do you have the vortec style intake to go with the vortec heads

 

Not yet but im gonna get one haha. Im most likely gonna try to find some pregapped rings and just change them on a weekend or somethin

 

Ya that would be your safest bet

 

Good info in this thread. One thing to keep in mind is that piston skirts wear just as fast as rings. Worn skirts cause poor alignment and affect ring seal. Even if you don't get the cylinders machined, it is a good idea to replace pistons along with rings. If not machining the block, just replace with OE stock pistons, no overbore. You will be amazed how much tighter the new pistons fit in the cylinders. That's how much the skirts wear. Any half decent machine shop will hang pistons on your rods for pocket change.

Before removing pistons to do rings and pistons, check for a ring ridge at the top of each cylinder. With high mileage, I would be surprised if your engine doesn't have it. A carbon build up ridge is okay, you can scrape it away with a razor blade. But, if you can catch a finger nail on the metal ridge left behind after scraping, you may have little choice but to get the cylinders honed. The ridge is equal to cylinder bore wear. You may also have a fun time pushing the pistons past the ridge on removal. There is a tool for this called a ridge reamer. I've gone through a couple because the ones I had were chintzy and didn't last long. The tool cuts the ridge down smooth to allow for easier piston removal.

Whether you do pistons or not, if you're doing rings you must renew cross hatch using a ball hone in a power drill. Operate the drill at about 1,000-1,500 rpm and move the hone vertically in and out of the cylinder at a rate that produces about a 45degree cross hatch. Keep the cylinder oiled as you operate the hone. After honing, wash the cylinder walls with Dawn dish soap and hot water. Blow everything dry with air and spray the rod journals and cylinders with WD40 to prevent rust.

Without good cross hatch, your new rings will not function correctly. 240 grit hone is about right for stock cast iron rings or iron/moly combo sets. You can do the hone with the crank installed. Just be sure that the crank throw for each cylinder is at BDC and cover the rod journals with a cloth.

Also, while you're at it, rod bearings wear much faster than main bearings. I generally roll in a new set of stock size rod bearings along with rings and pistons. It's cheap and good insurance.

 

Ya if it was me I'd rebuild the whole bottom end with all new bearings and change all the bolts to arp cheap insurance for the bottom end specrazy with high miles

 

If i could avoid honing them thatd be great. This motor is just to get it driving and running pretty good and kinda fast for a couple years until i build a stroker thats why i dont really wanna remove the crank and damn sure dont wanna buy one ot else id just get a stroker kit haha

But from what i see it looks like imma hone the cylinders and just cocer the journals real good