That groove appears to be deeper than I like so I would pull the motor apart to find out what is going on in that cylinder to find out what is causing that

That groove appears to be deeper than I like so I would pull the motor apart to find out what is going on in that cylinder to find out what is causing that

The scratch is allowing the carbon to settle in the groove
I use file to fit ring sets in all the motors I build (1000s+) and I use a small hand sharpening stone to deburr the ends of the rings on all four sides and now and then I still will see some of those lines in the cylinder walls while assembling them When I do I make sure there are no sharp corners with burrs in those rings
Those scratches will stay in the cylinder walls for a while, if it does not use oil and it has a good compression test or and leak down test then run it

I'm doing winter testing on my bracket motor now, it leaked down to 70/80 on the worst cylinder and 78/80 on the best cylinder, three plugs where clean and two had noticeable amount of oil on them I had ran it in neutral several times to warm it up for setting the valve lash, three needed a tiny bit of tightening, several needed loosening up and 5 or 6 where okay. I set them at .022 warmed up this time and I will write that down in the racing log book for this year I'm not sure exactly where I had set them last year
I run pump E85 fuel in this motor, it has right at 15.0 to 1 compression ratio with real narrow rings(1MM) with low tension oil rings for the vacuum pump.
I had the crankshaft bolt come loose on the last run last year and it and the pulley came off during a run so the motor has been ran since then without the pump. I'm sending the pump in for checking and rebuilding if needed, that is probably the reason for the oil on some of the plugs It hadn't had any sign of oil on any of the plugs I've checked or change at the track last year with the pump working
Hopefully this years results will be better

Thanks alot for your answer!
Im going to do a leak down test and get back with results.

Is this a drag race engine? Do you make runs with no air filter? The third picture looks like dirt may have got in there as there are numerous vertical scratches in that cylinder wall.

Looking closer those scratches are really uniform and evenly spaced apart like the oil ring scrapers are not holding the center section of the oil ring in place. Maybe that rough crosshatch wore the oil ring scrapers down letting the center section rub more than it should or, one of the scrapers seated above or below the center spacer letting it come out and rub the cylinder wall. Whatever the problem is that oil ring center spacer should not be out against the wall making those marks.

Sometimes we all imagine the worst things when we first see them
Further testing and investigating can help us under stand what is bad and not so bad
Yours is good, in my opinion

Hows that even possible for the oil rings to move around in the cylinder like that when the rings are properly assembled? And belive me they are properly assembled, i have been almost redicoluos meticulous with this engine.

Hey, Just reading what the pic shows. You said all the other cylinders look good and this one has the marks so there's something causing them. I'm sure you installed the rings correctly. We always hear the snapping of the rings as you install the pistons into the cylinders upon assembly, one oil ring scraper could have snapped out of place during the piston installation into the cylinder. That's all it would take.

Im greatful for your answer, im just wondering hows it possible and should it not be any recistance when you turning the engine over after assembling the pistons, i remember i check for any additional recistance after each piston been assembled with a torque wrench and when i have all 8 assembled i had 20 ft lbs to start the crank rotate and between 10-15 ft lbs to keep it rotate even through the whole revolution, but maybe the spacer between the oil rings doesnt do much to recistance i dont know but thats how you use to do for check if their is some error, i not record anything strange on the cylinder walls either after turning the crank over and over checking for some recistance during the revolution.

[quote=Mopar493][quote=GODSCOUNTRY340] We always hear the snapping of the rings as you install the pistons into the cylinders upon assembly, one oil ring scraper could have snapped out of place during the piston installation into the cylinder. That's all it would take.