Cylinder wall scratch question

[Road_Tripper]

Hoping someone can help me with a question. I am going through my 223. It had a lot of blow by, so the plan was to just clean out the head and motor, lap valves, hone the cylinders and just make it better than it was, but keep it a budget build due to limited budget. The goal is to have an around town weekend driver (no long trips or highway driving), not looking for performance, just reliability

When I pulled the pistons the rings just fell out and were broken. I have a deep scratch on the #1 cylinder and wanted to get your advice on what would probably happen if I didn't pay to get it bored and just put new pistons and rings in it?

My question is basically, can I put in new rings and pistons and have my around town driver or will it cause damage to the engine trying to drive it with this scratch? Appreciate any help/advise!

 

[DON]

I see there are some other areas that didn’t get “ scratched”. Those are areas that will loose compression and cause blow by. It looks like the block is pretty much stripped down, and going to the expense of pistons and rings, it would be a shame to not get it bored at this point.
The ol’ rabbit hole
Budgets are a pain

 

[sixtseventwo4d]

The scratch doesn't concern me as much as some of the other areas left untouched from the hone. These are the areas prone to ring seal problems and possible breaking.

 

[manglass]

That scratch looks pretty deep to me. I don't think your blowby situation will improve much if you rebuild around it. In fact, you might quickly break your new rings. I would bore that cylinder just to make sure that scratch isn't a crack.

Lou Manglass

 

[Blairsville Ed]

Ultimately, it comes down to cylinder roundness, taper, and piston to bore clearance.
You might be surprised how worn this cylinder actually is. Putting a new piston in a worn bore causes the pistons to rock back and forth and upsets the ring support which will create a bad seal. At the very least, get a good measurement of the bores geometry.

 

[Road_Tripper]

All good points to think about. Thx!

 

[DON]

You didn’t happen to do a compression test before tear down did you?? That would give you a little more insight to what the rings are doing

 

[Frank]

All good points to think about. Thx!

Also, some thought needs to go into discerning why the rings broke. Extreme early timing or misuse of ether starting spray. Anything that causes extreme cylinder pressure can break a ring. . Maybe end-gap too tight, but the cylinder condition appears to not support this theory.

 

[Bill56]

If your budget is real tight and your pistons still good, then new rings will be way better than broken ones.
However, if I were going to be buying new pistons, I'd get it bored.

 

[Road_Tripper]

You didn’t happen to do a compression test before tear down did you?? That would give you a little more insight to what the rings are doing

No, I didn't. The reason I took it apart was that the blowby was pretty bad. I did have about 50lbs of oil pressure, so was surprised to find the rings in pieces

 

[Road_Tripper]

If your budget is real tight and your pistons still good, then new rings will be way better than broken ones.
However, if I were going to be buying new pistons, I'd get it bored.

I have 1 damaged piston that came out of a different cylinder, but funny that no scratches or issues with that cylinder wall

 

[Frank]

I have 1 damaged piston that came out of a different cylinder, but funny that no scratches or issues with that cylinder wall

That looks like heat damage, which goes with my earlier post about ignition timing possibly causing the ring breakage. When you get it back together, verify timing and fuel ratio. Very early timing can cause both these situations, as well as lean mixture. (Or engine running hot, or excessive exhaust backpressure. Verify no severe exhaust restriction, or stuck heat riser valve.)

Just my input- Except for the one deep scratch the walls look good. tight budget: measure the cylinders, based on the clear hone present they are probably ok. If so, use new pistons and new iron rings (not molly) of the same size as removed, and button it back up. (Obviously verify ring gap). You may have some higher oil consumption in the scratched cylinder, but probably not extreme.