Normal piston ring wear pattern? Picts inside

[Pablo]

I have pictures of two pistons from my recent engine build. I tore it down after a few hundred miles when the crappy felpro head gasket gave up.

I noticed the piston rings have an uneven wear pattern and I was wondering if this is normal or something to worry about.
The rings are speed pro file fit plasma-moly

Here are the pictures, the first picture is a piston where the second ring still has a dark grey coating around its circumference:

now take note of this second picture, the second piston ring has had the dark coating worn away:

is this kind of second ring wear normal? should the top ring on both pistons look the way it does?

 

[KL Mallender]

Wear looks perfect, 2nd ring is tapered down(scraper or reverse twist), no carbon between 1st and 2nd means no blow-by, yer looking good.

Kevin.

 

[dr_frankenstein]

did you use a torque plate during the boring and honing process? were the mains torqued down?

A.j.

 

[Pablo]

Thanks Kevin, so the slightly different second ring wear is nothing to worry about?

Dr. Frankenstein,
No and No

I''m not to worried about that aspect of it.
Do you think that has something to do with it?

 

[dr_frankenstein]

bore may be round when bored without a torque plate, as well as mains.

when assembled the pulling of the fasteners may have caused a slight amount of bore distortion, meaning when its assembled the bore is not Perfectly round.

A.j.

 

[Pablo]

Oh I'm aware of the idea behind the torque plate and torquing the mains. I still have yet to see anyone post measurements that show it's a factor in a 109. The only person who's ever measured found no difference in bore distortion before and after torquing down heads on a 109. I was meaning to measure it myself but haven't found the motivation to do so.

 

[KL Mallender]

Hi Pablo, all 2nd rings have a taper that is used to scrape oil from cylinder even though they are called 2nd compression rings, so you will always see the wear pattern on the lower edge of ring which is in contact with wall. Upper rings are usually "Barrel Faced " to accomodate for "piston rock" ( slight tilting of piston ) when moving from BTDC to ATDC, some upper rings may be used in specialized applications : L-shaped or Dykes for use with gas porting and other "Tricks". From the wear I see : full contact top, clean even lower edge 2nd, no sign of combustion past top ring, no oil upwards of 2nd, you've acheived the proper ring seal, Job Well Done. :biggrin:
Clean her up and put her back together, you're golden.

Kevin.

 

[Pablo]

Thanks for the info Kevin. I feel a lot better now about it.