[Adamant1971]

Early 78 4.5.

Obvious signs of a foreign object in one cylinder. Going to pull the pistons. I was hoping to do rings and rod bearings and not split the block.

But I guess if I have to get the block decked I will have to split it.

Slippery Slope :)

[worf]

IMO, weird for only one cylinder to show that damage and not others. Something specific happened to that one (e.g. ate a spark plug tip, someone dropping something into it during service, broke a ring just a bit, etc.)

Can you get an oversize 4.5 piston? (Might not be a relevant question as I don’t recall bore specs 4.5->5.0.)

Lotta work to have a “good’ 4.5. Engine swap candidate?

[Adamant1971]

My goal is to keep this car original and with its matching block. It’s a rare early 78 Euro continental orange.

It does look like it might have chewed a spark plug electrode or another small metal object.

I will pull the pistons tomorrow so I can measure the bores snd inspect the piston skirts, rings, etc.

[worf]

My goal is to keep this car original and with its matching block. It’s a rare early 78 Euro continental orange.

Cool. Makes sense.

It does look like it might have chewed a spark plug electrode or another small metal object.

An M6 washer or similar-sized. Bounced around for ~100 strokes then exited. That's what caused the damage like that I've seen before.

Any visible damage to valves or seats?

I will pull the pistons tomorrow so I can measure the bores snd inspect the piston skirts, rings, etc.

Cool. Post back.

[Adamant1971]

Pan is off. Very thick sludge in the bottom of the pan.

[Adamant1971]

Pistons are out.

-Piston skirt coating is worn off
-#7 has 2-3 small marks that can catch a fingernail
-#7 piston has small gouges on side above rings from a metal object
-Rod bearings are not overly worn