The high performance/race rings which are .005 oversize and require grinding end gaps are a lot more expensive than standard rings and most engine builders would not get them for a stock rebuild or a hot street build. You could check the parts list for a part number which would reveal whether they required grinding or were standard replacement rings. We build around 600 800+ HP engines a year and we often see worse bore scratches than you have after just running on the dyno. We bore scope every cylinder as part of our post dyno inspection. If the gaps required grinding it would take a very sloppy engine builder to forget to deburr the rings. He would probably catch it when he put the ring on the piston as a burr would snag in the ring land and would not feel right.

 

greg, are you referring to "file to fit" rings? not the situation in this thread, but when cylinders are over-bored, i would hope any engine builder would opt for this type, and NOT standard rings. in a align-hone clean-up yes, standard rings.

am i right?

 

Ok But as you said that the engines you build often have more bore scratches then what you se on my pictures. Then perhaps my engine builder did do everything ok, and the "wear" i got is pretty much normal?
My engine builder is out of town, I will confront him with those question as soon as he arrives back. I just need as much info from others before that.
How much scratches and how "deep" scratches do you as a engine builder "allow" before you tear a engine appart?

Thanks

 

The rub marks you see are normal and there is not much you can do about that. A scratch you can feel with your fingernail is not normal but may not be serious enough to do anything about either. Something caused the scratch, improper honing, perhaps glass bead left in the cylinder heads that was not sufficiently cleaned, perhaps something that got by the air filter, perhaps the pistons were not clean enough before assembly, perhaps the bores were not clean before assembly or any other of a multitude of possibilities. If it were mine I wouldn't like it either but it may or may not be serious enough to try to fix. After looking a little more closely however, I see a couple of other things that would concern me more than the scuff marks and if it were mine I would probably go back in there for that reason I guess; it appears the choice of hone finish was a little on the rough side and my guess the rings probably scraped the peaks off the hone job a little. More important than that it looks like the ring seal is not too good. There is oil getting by the rings for whatever reason which should not be so something is not right concerning the rings. The best chance you can have is to hone the block with good Sunnen honing equipment to the correct finish as specified by the ring manufacturer to the correct piston to bore clearance and use good quality parts properly cleaned before assembly. Align honing refers to the honing main bearing bores when caps are torqued in place and honed to the correct housing bore size as specified by the bearing manufacturer by a Sunnen CH-100 line hone which uses a special long mandrel. Cylinders are best honed with torque plates properly tensioned in place to simulate cylinder wall distortion caused by adjacent cylinder head bolts. Bore size is dictated by by the piston manufacturer and if not followed either excessive bore scuffing or noisy pistons will result. Cylinder finish in microinches is always specified by the ring manufacturer and if not followed poor results will be obtained. Modern rings of good quality are lapped during manufacture and break-in is not really necessary anymore. They usually seal right from the beginning when everything is right and they are either right or they are not. I have not met an engine builder who can successfully second guess the manufacturer's engineers but have met many who talk in terms of "tricks." Tricks are for kids.

Regards, Greg

 

I forgot to ask...why do you have the heads back off. What problem were you experiencing?

 

I just got curios on how the piston and bores looked after 1 summer with the "new" engine.
So I did not experince any probleme.
And I already got the intake off aswell as the headers ( intake is gettin powdercoated, and the headers is getting coated ).

The car did not eat much oil during the summer, and the car really did preforme well. The only thing is that I thougt it should be more powerfull with my combo, but i still got som WOT tuning to do..

What you tell me about the rings dont sound to good What makes you come to that conclusion? is it the oil/carbon on the pistons?
And can a leakdown test verify that?

Regards

 

There are crusty oily deposits on top of the pistons and the places on top where oil has washed up over the crown keeping carbon from forming an even layer across the top. A leakdown test will not confirm anything like that. You should have seen abnormal oil consumption though. A leakdown test is really only useful for extreme wear or mechanical failure. It is too easily influenced by things like temperature and the presence or absence of oil.

 

It appears that the engine was probably honed without torque plates. If that is the case, it will use a bit of oil.

 

I must verify that with my engine builder.

As I posted in a previous topic here on corvetteforum I hade some probleme to tune the car due to 2 faulty injectors, so the engine has runned lean on some cylinders and rich on some others. As well as a bad pcv vavle.Perhaps this could contribute to the oil?
This has now been corrected. I provide you more pics on how the piston looks.
As you can se on all of the pistons the lower part has less oil/carbon buildup, thats becuase I started to clean some of the pistons.

Regards

 

Most engine builders will tell you they used torque plates. The reason I suspect that yours may not have been is easily seen in the photos. On a motor that is honed without torque plates, the cylinder is perfectly round(if he honed it properly). When he does this, then you install heads, the cylinders will pull in at the top of the bore. This will leave a shiny mark on the cylinder wall, where each head bolt is. The pull of the bolt , shrinks the id at the top of the cylinder, then the rings grind tightly on the metal displaced by the head bolts. Those 5 spots seal tightly, the rest of the cylinder, not so tightly.
A motor that has been torque plated will have little, if any shiny spots on the cylinder wall near the bolt holes.

 

Its funny you mention the "shiny mark on the cylinder wall". When I whas out and took the photos I provided here. I took a flashligt and I look carfull in the bores. And as you just said I got some "shiny spots" on the wall. So you are indeed correct.

So I guess im must make a decision soon. Either I accpet the fact that it has some ''skirt scuffing'' and some tiny scratchs, that ( according to the replys in this topic ) is not that unusal. And that the block has been honed without a torque plate and therefore will eat a bit more oil then otherwise.
Or I take the engine out and start over again. And for that I dont have finance as for now. So it will mean a summer without the vette..

 

I would not lose a wink of sleep over the skuffing. The 5 shiny marks are a problem(possibly). I would not go the summer without if it were possible. Slap the heads back on and enjoy the car. At least for the summer.

 

Thanks m8

Regarding the torque plate honing.
Is it always true what you are saying, that if you dont use a torqueplate you WILL end up with this "the 5 shiny mark probleme".
Or im I just unlucky that I got this state?

If yes, that must mean there are thousands engines out there that has the same condition, and the owners to those cars are happy unknowing.
Becuase Im sure im not the only one with rebuild engine where the engine builder did not use a torqueplate..

Regards

 

I became educated in this matter by building a motor with a local, reputable builder. It was nothing but problems. Upon taking it to another honest shop, I witness the hows and why's of torque plate finishing. Based on the few I have seen, the motors with a torque plate will still have a slight, very small shiny mark, even if torque plated. Much smaller than a pea. If they are thumb nail size, it was likely not honed with plates. The proof positive way to check is to plunge a bore guage down the bore. If it is round without the head on, no plates were used. If you remove the rod and piston, torque the head on and bore guage it from the crank side of the hole, you may find distortsion as much as .003-.004 or more. I could not believe just how much torque plates help. You are correct though. Many are charged for torque plates, some get them and some do not.

 

So how can I tell if my engine work ok, is there som sign I can look out for during this summer. Or do I need to take off the heads next winter as well?

 

A bore guage is the only way to check the cylinder properly. This can be done with the engine block in the car and heads off. Simply put the piston down at the bottom of the bore to check it.

 

It is do-able with an inside micrometer, but it's a real PITA and takes some experience. I'd lend you my bore gauge if you were a little closer!

 

what we're experiencing here is the dark scary side of having an engine rebuilt, built up, or just refreshed. you may think you know your builder, and he may lie to you thru his teeth. the sad fact is that its all very hard to prove and pin on the builder, and he will fight you every inch of the way. he knows all the ins and outs, and will dance very neatly around every argument and counter argument. builder seldom admit anything especially if it costs them time. time = money, which is what he's in business for in the first place. he hates to spend time or even more money for parts, fixing his own errors.

devilfish, i hope everything checks out, at least to a somewhat acceptable tolerance. there's no doubt there are many out there in your shoes. let's hope its as minimal as possible, and won't get any worse.

 

I will talk to my engine builder as soon as he arrives back in to town.

But the statement that Greg Gore said regarding the oil on the pistons, and what you ( Pete K ) said regarding the the 5 shiny marks is for me proof enough that this engine is not 100%. So perhaps the use of a inside micrometer is unnecessary. I dunno..

But how would you guys act in my case if the engine is working "fine" and preforms satisficing during this summer. And the "only" downside that I can notice from this is a bit more oilconsumption. Ofcourse within "acceptable" limits.
Or is it a ticking timebomb that will eventually break down. Perhaps hard for you guys to answer. But my plan is to use this engine and run it hard. And I got plans on building a new engine on the side. Or buy a shortblock.


Regards

 

Because I have been down that road a few times, I would suggest putting it back together and running it. The enjoyment of using the car outweighs the aggrivation of fixing it immediately. Next winter you will have your facts and options ready. Time will be on your side.