440 Cylinder Issue

[Scott 440 TNT]

I have a 72 440 that has two cylinders where the piston skirts are scoring the inside of the cylinder walls.
I can only see them from the bottom side.
What could be causing this?
Thanks

 

[commando1]

I have a 72 440 that has two cylinders where the piston skirts are scoring the inside of the cylinder walls.
I can only see them from the bottom side.
What could be causing this?
Thanks

Bad fit with the wrist pin and piston.
Bad fit with the rod and wrist pin.
Bad fit with the rod and crank.
Bad bore.
Bad piston dimensions.
How bad is it. Will honing clean it up or does it need to be bored.

 

[57fury440]

Are you getting any noises from them? What are the pistons? Factory or aftermarket? Cast or forged?

 

[70bigblockdodge]

Need more information info.

 

[Scott 440 TNT]

I have a 72 440 that has two cylinders where the piston skirts are scoring the inside of the cylinder walls.
I can only see them from the bottom side.
What could be causing this?
Thanks

Additional info
This motor came in a car that I bought and I haven’t tried to run it yet.
It looks like it’s been in the car a long time but isn’t original to my car.
It’s hard to turn by hand and with the starter, but has loosened up some since I primed it with oil.
It feels like it’s shuddering when the two cylinders on on the way up, most likely from the piston skirts rubbing on the cylinder walls.
I’ve looked at all the bottom end bearings and there wasn’t anything looking spun or badly worn or burnt.
The motor is still in the car with the heads still on. I’ve put a camera in the cylinders and all were decent and not rusty.
I think a light hone could clean up the scoring. Not sure what pistons it has in it.
Has a forged crank.

 

[1970FuryConv]

I have a 72 440 that has two cylinders where the piston skirts are scoring the inside of the cylinder walls.
I can only see them from the bottom side.
What could be causing this?
Thanks

Skirt is offset from the wrist pin/piston pin 90°.

Skirt wear may happen when there isn't enough clearance between piston and cylinder wall.
Or the piston got too big from overheating.
Or the piston is installed backwards, so the wrist pin and connecting rod offset is wrong. That makes a sound called piston slap, a sound that changes as load changes.

Regardless, the pistons need to come out. You'll have to measure the pistons and the cylinders to verify clearances. @Toolmanmike provided this pic in another thread.

 

[Scott 440 TNT]

Skirt is offset from the wrist pin/piston pin 90°.
View attachment 655591
Skirt wear may happen when there isn't enough clearance between piston and cylinder wall.
Or the piston got too big from overheating.
Or the piston is installed backwards, so the wrist pin and connecting rod offset is wrong. That makes a sound called piston slap, a sound that changes as load changes.

Regardless, the pistons need to come out. You'll have to measure the pistons and the cylinders to verify clearances. @Toolmanmike provided this pic in another thread.
View attachment 655592

Very good info and much appreciated.
I will pull the heads and check the pistons and other related parts.
The thrust side is where I see the wear.
Thanks

 

[70bigblockdodge]

I've been turning pistons, swapping from bank to bank, and engine to engine. I've had engines where I believe the pistons were too tight and definitely ones that were too loose. None of that caused scoring. Lack of oil, hot skirts will usually gall on the wall (aluminum piston material) transferring/sticking to cylinder walls) Scoring is almost certainly dirt or broken rings. Front to back scoring is most likely the pin has come loose and is gouging the walls as mentioned earlier.

 

[Scott 440 TNT]

I've been turning pistons, swapping from bank to bank, and engine to engine. I've had engines where I believe the pistons were too tight and definitely ones that were too loose. None of that caused scoring. Lack of oil, hot skirts will usually gall on the wall (aluminum piston material) transferring/sticking to cylinder walls) Scoring is almost certainly dirt or broken rings. Front to back scoring is most likely the pin has come loose and is gouging the walls as mentioned earlier.

Thanks for your input.
The two cylinders show scoring on the thrust / intake side.
I will be pulling those pistons looking for ring issues or something off.