Cylinder wall scratch. Bore or not?

[talonsteve25]

So just the other day my dad found a scratch on both 1 and 2 cylinders. The scratch in 1 is about 1 and a half inches and 2 about a half inch long. But i didnt even notice them they were so small, but you can feel them with a finger nail. So i was wondering how deep they have to be or how bad for me to have to go and bore the motor?
I can take some pictures if needed to.

 

[97 4G63]

Yeah ..take some pics that will help a lot on giving you an accurate responce.

 

[Burnett03]

Does your finger nail catch the scratch?

 

[talonsteve25]

Ok ill go out and take some. It does catch but not that much if you know what i mean i can feel it but i can still pass my nail by it with out it getting cought or stuck but i do still feel it. Pictures are needed

 

[talonsteve25]

k heres a picture

 

[Burnett03]

It might hone out but it's to hard to tell by pictures. The walls are scuffed pretty bad but that is normal in a way. If it were my motor i'd hone it at home with a ball hone and see how it measures out. If it's not ok and there are scratches bore it and hone.

 

[JayRolla]

If you know anyone thats good with dsm's have them look at it. I would at least hone it like Burnett said, its pretty easy. If it was me I would bore it .20 over anyways to be safe.

 

[MichaelSuch]

Hone for sure since it's already out. Also get that beast cleaned up a little. I would just take it to a machine shop and have them clean it/hot tank it to get all that oil off and if you want they could hone it for you or have it bored out if it needs it.

 

[JusMX141]

Those are skirt scuffs from the pistons.

Skirt scuffing generally happens when the cylinders get barrel-shaped. The problem doesn't fix itself with honing.

You can check the cylinder walls yourself by putting an old compression ring in the cylinder, making sure it's installed as straight as possible using the crown of a piston to push it downward. Take meausurements of the piston ring's end gap using a feeler gauge at three or four locations from top to bottom. If there is more than a .004"-.006" difference between any of the measurements, the block should be bored to the next larger size and oversize pistons will need to be purchased.


A machine shop will have a field day with that block....the bores are scuffed, the block is filthy, and the deck looks like a wreck and probably needs flattened out. When you get it back it will look night and day better than it does!

 

[talonsteve25]

ya yuck i agree with all of you. I am on a buget and really didnt wana really touch the bottom end but from the other side there is more scratches so i guess im just gona fork out the cash buy over sized pistons, rods, bore it, hone it, deck it then new crank and rod bearings, arp hardware. Holy wish i wasnt still in school .

So i guess where do you guys get kits or the parts? wheres the best prices? im so hooped being up in calgary i dont know any dsm places around here.

 

[dsm44130]

well in that case .. the motor ran before the head blew i assume so ball hone it and throw some new rings on if your just looking to get it on the road

 

[dsm03]

ya yuck i agree with all of you. I am on a buget and really didnt wana really touch the bottom end but from the other side there is more scratches so i guess im just gona fork out the cash buy over sized pistons, rods, bore it, hone it, deck it then new crank and rod bearings, arp hardware. Holy wish i wasnt still in school .

So i guess where do you guys get kits or the parts? wheres the best prices? im so hooped being up in calgary i dont know any dsm places around here.

I'm sure you can find a machine shop at the very least.

After that, your luck with finding parts for DSM's are just as good as mine, but I find them. Let me know how that goes and PM, I'll shoot you a few places you can try depending on what you need.

 

[kbiker76]

Look and see if the supporting vendors have any sales I know there was just a really good sale through MAP in the vendors section on pistons.

 

[95weclipse]

Those are skirt scuffs from the pistons.

Skirt scuffing generally happens when the cylinders get barrel-shaped. The problem doesn't fix itself with honing.

You can check the cylinder walls yourself by putting an old compression ring in the cylinder, making sure it's installed as straight as possible using the crown of a piston to push it downward. Take meausurements of the piston ring's end gap using a feeler gauge at three or four locations from top to bottom. If there is more than a .004"-.006" difference between any of the measurements, the block should be bored to the next larger size and oversize pistons will need to be purchased.


A machine shop will have a field day with that block....the bores are scuffed, the block is filthy, and the deck looks like a wreck and probably needs flattened out. When you get it back it will look night and day better than it does!

This would be your best bet, like he said the cylinders get "tapered" and its not good and cant just hone out. The machinist will true them and I agree with him 100% they would love to have that block bring the crank with you have him check it if its bad just see if he can get an oem one one, my guy got me one for 200 with acl race bearings. bring the rods and pistons and have him check the rods around where they connect to the crank to make sure they are in spec and in round. He will also need the new pistons or he will get you cheap ones to put on there that match the bore he does.

 

[aba60620]

From my experience, a ball hone will mask the problems in the cylinder walls because of the "flex" they have (all of the balls move independently). What I think you should do is get a brake hone, its the type that typically has 3 arms with a long stone on the ends. The reason I suggest this type is because if you have any irregularities in the cylinder walls, you will be able to see them (all the low spots wont get touched by the hone). If your cylinder walls turn out to be good, you could just rering it and throw it together with new bearings and gaskets. If they don't end up being good well then atleast you can weigh the costs of having a machine shop rebuild it, or possibly find a used short/long block in good condition.

 

[Justin_l_]

I don't know if anybody noticed this but this thread was bumped up from 2008... Hopefully the motor is back together by now!

 

[smorton]

Check out rock auto if you want a nice stock bottom end. That what I did, shipping was super fast, and the prices are amazing. (I shipped 1800$ and 120lbs in parts to my door for like 95 bucks)

 

[2GbTalonGuy]

take it into the mashine shop and have them mic it out to make sure the walls are all straight and within spec. If not it will need to be bored out some.

 

[TimF]

I got a question about this to. In one of my cylinders I have a scratch on both sides, and a small one in another. The cylinders were already honed and there still visible, but you cant feel them. I am running evo9 pistons that are brand new and new rings, and I cant afford to have the motor apart again to get it bored over. Wouldn't I have to get new rings if I got .020 over? or should I be fine with the scratches. money and time are a issue.

The motor was bought pre built by a guy that builds motors for GM, he said he didnt machine out the cylinders because he seen worse scratches that gave cars no problems at all when he put them back together. I am just a bit worried.

 

[BogusSVO]

Tim with what you are saying, you really do not have a choice but to run it.

But from what you said also, sounds like the builder did not care.

Until the cylinder bores are mic'ed for wear/taper/ round you have no idea how bad it is.

No, you can not bore a block .010 and just change rings (Are there even .010 pistons/rings made?)

 

[TimF]

sorry I meant .02 over I don't know were .010 came from.

 

[BogusSVO]

No, you would have to replace the pistons... Your PTW would be around .023 with the STD pistons and .020 rings.

 

[11Banger]

I'd bore & hone just to be safe....

Rather safe then sorry

 

[BogusSVO]

I'd bore & hone just to be safe....

Rather safe then sorry

I would agree, but he just bought this short block. So he is a bit upside down in an half assed built engine.

 

[TimF]

I already had the block apart to get it decked, and re resembled it. I cant afford new pistons rods and rings, believe me if I could I would. what is the worse that could happen with scratches? It already has been honed.

Also when I got it from the machine shop they didnt tell me anything about the scratches, unless they didnt see them, maybe they were not worried about them even.

is there a cheaper alternative to forking out 750+ for new pistons, rods and bearings, and the cost of machining and balancing it all?