ZERO COOL

When you put in brand new pistons, say to lower your compression, do you need to take your block to a machine shop and get it honed to allow the new pistons in the cylinder? I've never heard of this before.

BlueSi2k

Yes, you need to hone the walls in order for the rings to seat. If you've never heard of honing, I wouldn't recommend installing pistons yourself...

AVATAR

Yeah I have a friend that bought stock bore pistons for his Si and he just had them installed w/o any machine work. He now gets piston slap. Just have them give it a nice cross-hatch and call it a day.

BlueSi2k

You wouldn't get piston slap just from not honing the block. Did he check the piston to wall clearance? Its probably loose.

AVATAR

I know, he should have had it bored (slightly) to remove any scarring on the cylinder walls, but instead he installed stock bore pistons on worn cylinder walls. . .now he gets piston slap. I'm sure the piston to wall clearance is loose.

SpoolinSol

Well if he had it bored then wouldnt it be recommended to get overbore pistons ?? otherwise wouldn't there be even more piston slap then he's getting now???

AVATAR

Sweet mother of God! I keep yapping but I guess I'm leaving out details, yes if he would have had it over bored he would've gotten new pistons for his bore size. . .there

Flamenco-T

get a medium size honing stone, hook it up to your electric drill, makes about 10-12 QUICK passes along the cylinder walls, one pass up and down count as one pass...

you'll have a pretty good cross hatch pattern from it..

stan

sweet

iTrader: (5)

yeah it doesn't take long to do a nice honing job on the sleeves. just what Flamenco-T said. often times it's recommended to use motor oil when crosshatching the sleeves and also don't forget the throughly clean the sleeves/block before installing anything into it. the honing tool is $60-70 roughly.

Flamenco-T

you can rent the honing tools at auto zone, just buy a replacement stone

sweet

iTrader: (5)

that's true. i'm just so used to buying tools on sale or at discounts so it's easier to work on my next motor or job. that way i always have the tools needed and i don't have to borrow or rent them. but renting is cool too.

earl

If the cylinders ARE out of round, nothing but boring and new pistons will work. ANYTHING you do to or for an out of round cylinder, will do no good because it just won't seal properly.

TheSwift1

sweet

iTrader: (5)

yeah you can't do much with a higher mileage motor that has out of round bores.
i've seen them before, and only a quality honing job will fix that and then of course the bores are larger so you need to use slightly oversized pistons.

the block i've been working on had low mileage and the cylinders were perfect, so i just picked up the cross-hatching tool and gave them a quick honing for the new rings. the cost of getting the cylinders rehoned is about the cost of getting the tool around here. so if you don't need boring to get rid of out-of-round cylinders then it doesn't hurt to just get the tool and do it yourself. then next time you need to crosshatch a block for new rings, you already have the tool and don't need to pay to have it done or rent one. but if you need to overbore the cylinders then getting it done professionally is usually the way to go, and the crosshatching tool isn't needed.

LSiTurbo

...it doesnt have to be taken to a machine shop. Just get a ball hone and put it on a drill...

sweet

iTrader: (5)

yeah you could do that also, but it may not be as accurate as having a machine shop do it. but that depends on the tools the machinist uses to do it.

lazerus

I nominate this thread for Newbie of the month award!

If there isn't one, i say we create it!

AVATAR

*looks around* why because EVERYONE with the exception of LSiTurbo has been on here longer than you?

DIRep972

iTrader: (1)

owned!

good info on this post though, hopefully no one will ever buy stock bore pistons and install them without proper honing and clearances again.

AVATAR

W3RD