Check out this one Dator boys

[80spitfire]

Hey guys,
I split the case on my Dator tonight, boy was that ever easier said then done The crank appears to be in really nice shape. Supposedly it was rebuilt the motor rebuild before I got it. Anyways, I checked out the pistons that came out of it tonight and I was pretty surprised with what I saw to say the least. It turns out they put one grooved piston in with one smooth piston. Interesting right? The guy that had it before said it burnt down almost right away after he rebuilt it. Now I know why. I would have loved to have had some compression numbers on this motor as it sat with those pistons.

[ICCSF 108]

It looks to me like something was ingested to the top of the piston & was caught in a port or when the installed the piston they either broke a ring or had the wrong end gap tolerance.. I would check the crank & ports real good to make sure there isn't any small pieces laying around in anything that could let go once the engine is fired up..

Kenny

[80spitfire]

That definitely sounds likely. Yeah I'll check the ports and I'm sending the crank to Jerome next week.

[I500]

I have seen that one before. Roller off the lower rod bearing. Hope i,m wrong

[80spitfire]

I doubt that's it personally. The crank looks beautiful and spins very smoothly so I'd be quite surprised. Here's a picture of the crank also

[HoosierDeereMan]

80 Spitfire,

I had a very similar incident happen with my 340/s. My cylinders were worn .012" to .014". The wear allowed the piston to cock in the bore and hang a ring in a port. My piston looked very similar. Your's looks like it happened on the upstoke. Mine happened on the downstroke.

Troy

[80spitfire]

Hmm that's an interesting take. That very well could be the cause too. I'm dunking the piston in carb cleaner to see if it was even the right piston to begin with too. One thing I also wonder is that if the piston was put in backwards. If it was that would cause the ring pin to catch a port.

[HoosierDeereMan]

It looks to me like the damage on the piston lines up perfect with either the intake or the exhaust port. Another thing is the ports should have chamfered edges to aid in keeping this from happening.

Troy