Sommer86

iTrader: (46)

What could possibly cause these 2 perfectly centered "dimples" in the pistons face, in each depression?

I've heard they're fine to run, I just want to know how something like this is caused...

Tainted

iTrader: (9)

Fuel/air wasnt correct and caused it maybe?

MMWS6

I would hazard to guess that it was a centering tool used to mark those reliefs out in the piston. You just took these out and found this or this is the first time they have been in the car?

WS.SIX

iTrader: (3)

dimple made to keep ptv checker in place?

Tainted

iTrader: (9)

The one hole on the left looks like it is cracking outwards.

KCS

iTrader: (20)

That's what I would guess. The piston either didn't have reliefs at all, or were cut to small or shallow.

Sommer86

iTrader: (46)

thanks for the guesses guys.

I just found these on my pistons. But it's only on the #3.... of the forged 402 I'm building.

Gates72ss

That little piece sitting there looks like ti would drop right in the left dimple...Just clean these up?

ironmanLS1

iTrader: (9)

Just knock the high spot down and dont worry about it. Someone ran a center down through the guide.thats all.

LS1MCSS

iTrader: (18)

Looks to me like the tool used to cut the valve reliefs had a small pointed end sticking down and they went just a little bit too far when they were cutting the piston for PTV clearance. If you look at the second and third pictires, you can see that the dimple is on the same angle as the valve relief.

JakeFusion

iTrader: (7)

If it's a Wiseco or Diamond piston, just call them up and check with them. They may even replace if it's deemed a QC issue.

Mell00

LOL.....

That is where the engine builder marks the pistons with the head on the block to know where to center the tool when they cut the valve relief.

Jeez.....

chrisfrost

iTrader: (8)

Yes I agree , You can clearly see that the holes are centered where if those cut outs were a full circle the centers would be .

3rdCoastPowerSports

iTrader: (5)

Looks like the exact mark my bluepoint auto center punch makes

JakeFusion

iTrader: (7)

I guess my question is - did you or the machine shop flycut? Or did you buy them with the valve reliefs in them? They look like they were purchased with the reliefs. If that's the case, it still looks like a QC issue. If it was done at the machine shop, they did nice work on the reliefs, except for the punch marks.

Sommer86

iTrader: (46)

Thanks guys! This is exactly the kind of info I was looking for.

Now, How do I "knock down" the high spots on the piston face?