How much piston damage is too much?

[sfinsf]

looking for input on the condition of my piston surfaces. How much damage from exhaust valves is too much?
Shown in order of least to most damaged. The other three are not any worse.

I've searched and seen other posts with similar questions but nothing really addresses a "cutoff" point when damage is too great. What happens then?

read that a debur is needed, any other input?

My head is being completely refreshed.

[jeffnhiscars]

I dont know how you would debur those without getting metal fragments where you dont want them, but they are no worse than mine were and it runs better than any stock M20 I have ever heard. As long as there is no crack that travels over the edge to a ring land, I think they are ok

[monsterm20]

Kinda depends on the use ofthe motor. If it's just a stocker no mods or very light mods the I think they are good. But I would say if there is any crack don't use them. Nothing worse than having a piston come apart at 6000 rpm under boost.

[sfinsf]

thanks guys, this is strictly a stock beast, DD for my wife

[jlevie]

I'd use a scraper to deburr the damaged areas, blow the swarf away and put the engine back together. The damage isn't that bad.

[dougie30]

dosnt look bad at all