Predator 212 piston blowing

[There_goes_me_rod]

So I had finally got all my mods(listed below) and about 30 minutes after running my piston blew into pieces. I was using e87 for fuel. Bent the billet rod also.
Mods
Arc billet flywheel
Arc billet rod with .002” extension
Mikuni vm24
12lb valve springs
Mod 2 cam

 

[Pk in oregon]

Rod to long for dished piston, what head gasket

 

[Pk in oregon]

I'm guessing that's.020 longer rod

 

[There_goes_me_rod]

Rod to long for dished piston, what head gasket

Yea that sounds like it, and it was a .020 ext. I had a thin metal gasket for the head.

 

[bpoirier]

You can clearly see the the piston had been slapping the head. You have to maintain at least .030 piston to cylinder head clearance.

 

[Pk in oregon]

Lesson learned, mines running at.027 p to head clearance and that worries me ,but so far ok

 

[BigMoneyGrip]

You need to use more sealant on that side cover...

 

[Codyb852]

Did you install the piston with the arrow facing down or up? It's setting sideways in the picture is why I ask.

 

[RadialFin]

Did you check piston to head clearance during assembly? I tend to agree with those saying that it looks like that piston was slapping the head prior to the total failure.

 

[There_goes_me_rod]

Did you check piston to head clearance during assembly? I tend to agree with those saying that it looks like that piston was slapping the head prior to the total failure.

No I did not check piston to head clearance. I still have the head and will post what it looks like.