Re-use U20 flat top pistons with valve strike dents ok?

[AltxF4]

Working on my Roadster, and thinking I may built a R20 for it with the parts I have around. The U20 pistons I have are 0.75mm over, and one piston has a few small dents from a valve that let go. I don't see any cracks, but have not done a dye penetration test yet. If the dye test homes back clean, is there any concern over re-using these pistons?

[JT68]

If they zyglow ok, should be a non-issue.

The more common problem is skirt cracks. If you remove the oil ring and look at the oil slot, sometimes cracks develop to the ring lands. Those will progress to the skirt. Its worth checking for.

If no cracks and the skirts don't have scuffing/wear, you should be fine.

[tjp]

Not to hijack but this is along the same lines......

How about minor pitting on the tops of the pistons? I assume that is a no go but would have also assumed that minor dents would be a no go as well so I have to ask.

[JT68]

Just depends what you are trying to do.

First class, long life rebuild: new pistons of course
Race engine: new pistons of course

Budget rebuild, but still ok: yes, either of the pistons described above would be fine as long as uncracked and unworn skirts.
Minor imperfections on the top simply fill up with carbon over time.

J

[AltxF4]

Good to know! I plan on running this motor for a bit while I debate if I want to do an SR swap. If I don't do the SR down the road, I will do a re-build with new parts at some point way down the road.

[fj20spl311]

I would check to see that the ring lands and grooves are good also.

[AltxF4]

So far so good. Trying to get them really clean so I can do the dye pen. On a sports similar note, is there anywhere I can buy a set of wrist pins? This set I got from somebody you left the wrist pins out in the weather and the bubbled the chrome and rusted good.

[JT68]

You could probably have them made, but it's probably more economical just to buy a new set of H20 pistons.