GS977

i got my motor back from the machine shop and am ready to start assembling the motor. problem is the pistons, whats a good way of cleaning the ring lands on my pistons. the old rings were stuck in the pistons. the tops of the pistons and ring lands have carbon buildup. not that much in the ring lands but the rings would hardly budge. i got all the old rings out (in pieces) and am ready to install the new rings. what about soaking th pistons in laquer thinner for a day or so. would that dissolve the carbon without hurting anything?

yellow 72

I just break an old ring and use it as a land scraper

markids77

Has your machine shop seen those pistons, and did they recommend their re-use? I ask because not only do the pistons need to fit the bores I am certain the shop prepared for you... sight unseen is unheard of... but those pistons need to be in good shape for re-use. If so, the easiest way to clean the ring grooves is with a bit of a broken ring... be careful, go slow and don't twist the ring which widens the groove, or let it escape the groove and scratch the outside. Personally, I would never re-use a set of slugs which had oxidized enough to seize the rings....

dannyman

I agree with both posts. What exactly did the shop do to the block. If only a bath and buff then go ahead and re-use the pistons, provided they go back where they came from. Broken rings are a good clean tool.

427Hotrod

Be VERY careful cleaning ring lands. Ring seal is created between the ring and the bottom of the ring land. If it's all scarred and scratched up you're going to have a smoker.

JIM

forvicjr

Buy new pistons,stock replacements with cost of rod fitting is still cheaper than pullin engine back out and doin a complete redo

JimT

I've soaked them in brake cleaner then buffed them out before and all worked well, but, you really need to check the fit! Also check to see if there are any nicks in the ring seats.

gerry72

Go to your local Lowes or HD and pick up a gallon can of paint stripper. Containes methyl hydrate and is an excellent solvent for carbon and coke buildup on the piston top and ring grooves.

TimAT

For $20 why not use the correct tool? Be careful- it IS possible to cut the top off a piston.

http://www.sjdiscounttools.com/lis24000.html

billla

I'm hesitant to jump into the fray, but what exactly did the machine shop do?

If the bore wear was such that you can reuse the existing pistons, I'd still mask off the lands and glass bead them. I've also used a ring chunk as a scraper - I've actually never seen the tool linked other than in factory service manuals. But, I can't remember the last time I reused a piston given the price of a set of cast pistons.

GS977, recognize that no one's being critical here - you just made a request for information that leads to other questions

7T1vette

If you have aluminum pistons, you need to be very careful when using 'broken' piece of piston ring to clean the grooves. The bottom of the grooves has a radius at each end of the inner seal land. If your square-edged piece of ring cuts into those radii, you will create a stress riser which will greatly weaken the strength of the piston. Under heavy load, such a stress riser can propagate a small crack and the top of the piston can snap off. Use the proper tool after you have soaked all of the crud out...or at least loosened it up. Also, some paint strippers/solvents are very damaging to aluminum. Select your 'cleaner' wisely.

yellow 72

As opposed to the cast iron type?

midyearvette

if indeed your pistons and rings are in that bad of shape....i would really question the clearance of the new rings in the old ring lands..if sloppy , you will be doing this repair again....buy new slugs...is the machine shop aware of this issue??.....


ps. if indeed the old slugs are servicable and you have never done this before, then buy a groove cleaning tool, if you have never used an old ring to do this, don't try learning now...jmo..experience is critical here!

Ironcross

Have the shop glass bead the ring lands of the pistons removing all the carbon including the top of the pistons.....You dont want any carbon behind the rings....

chevymans 77

When rebuilding our outboard drag motors we would use easy-off oven cleaner on the pistons, works pretty good. Tape the piston off and spray the ring groves, let them soak until you see the carbon dissolving, let sit a little longer and rinse.

The ring groves are critical, they need to be flat and true.

We would spend hours working on rings, we had a piece of granite ground flat to face the rings. You would be surprised at the deflection of the ring when squeezed into the bore.

I agree with Jim, be careful if using another piece of an old ring. I would not recomend it.

Neal

GS977

thanks for the help guys. i used oven cleaner and a brillo pad and a piece of old ring and the pistons came out looking new. the pistons just needed to be cleaned. it was a low mile crate motor. the machine shop said the block looked good. no ridge or scrathes in the cylinders. they just honed it for the new rings. and put new cam bearings in. they said the pistons looked fine also. they polished the crank, it looked fine also. i also got a set of 1990 l-98 corette aluminum heads, they did a valve job, surfaced them, set up the new springs,ret, locks, and seals. the guides were fine they said. new rod and main bearings.
i've never used cast pistons before but this motor will only make @ 300hp and there was nothing wrong with the pistons so it would of been a waste to not reuse them.
this is what i have, what do you guys think of this combo? how much hp am i looking at. i think @290-320 chp
std bore 350
@9.5-1 comp ?
1990 stock l-98 vette alum heads 58cc
comp cams pro magnum 1.65 rr
isky 270 mega cam .465/.465 221/221@.050 108 lc @ 1.5 rockers i have 1.65s so it will be .511/.511 and a couple more degrees duration.
cloyes true dr chain
edelbrock perf rpm intake
barry grant 750 dp
new 700r4 trans with @1500-1800 stall conv
this is going to be pretty much a dd with a/c 82 vette.

billla

Good luck with your build!

BLOCKMAN

If those ring lands are worn out in most cases they are and if you can slide a .002 feeeler gauge between the ring land and a new ring replace the pistons.

GS977

ok i'm just going to get new pistons. which ones? my heads are aluminum 58cc and i want to run 89 octane pump. whats the most comp i can run. i'm just want cast or hyperuetetic ?sp
tia