ring question

[animal22]

when checking my ring end gap it is less in the middle of the clyinder than it is at the top is this normal?

 

[keithcar72]

it just means the cylinder is out of round.

 

[Kart43]

Cylinder has taper.

 

[Outrider]

Or is football shaped. After awhile cylinders generally wear enough that the ring end gap is less at the top and bottom than in the middle - think of it as double taper.

 

[Jimbo]

If you are using the wrong type of hone, method or technique it will often give you cylinders with irregular shapes.
Even a small amount of irregular shape can cause a poor ring seal / ring flutter.
Imagine what the ring is doing at 7500 rpm.
Its traveling 33060" or 2755' per minute or 46 feet per second.

 

[gregh]

Not normal but as Jim said maybe someone honed it barrel shaped because they kept the hone running in the middle for too long for some reason. Time to overbore or get a new block.

You are pretty good with numbers Jim its 45.92 feet per second but who's counting.

Cheers Greg

 

[jjchat]

How much difference are you seeing?
Are you seeing the difference at the 12/6 position and/or the 3/9 position?

If it is only at the 12/6 position, this is a sign of wear and is not uncommon (although it is typically found more towards the bottom of the cylinder). You should bore and hone the cylinder straight.

If it as present at 12,3,6,and 9 o'clock, not only would I rebore, but I would look for a different machinist.

 

[Kart43]

You did not state how much time is on this engine. It is not uncommon to encounter excessive wear at the top of the piston ring travel. This is the point of highest temp., highest ring pressure, fuel wash down and carbon. A well worn engine will show a ridge, it should not be easily seen or felt in a competitive engine, but in a worn out car engine you can catch your nails on it.

 

[Freezeman]

46 feet per second.... I could withstand that easy, it's the 250 times per second that it stops and gos the other direction is what would mess me up.

 

[PD Power]

Get a bore gauge and measure.
Needs to read the same all up and down the bore, and all around.

Right now, you will need to either bore to the next size, or with a gear hone, hone it round.....and no taper, top to bottom.
I doubt very much that you will be able to "fix" this with a hone.

 

[jjchat]

PD: No way to fix it with a "ball hone" but you could with, say, a Sunnen hone. I would rather use an EZ Bore or other fixed boring device, but I know of several people who will go oversize using a sunnen.