5.0 Engine Rebuild

[Rocket]

I am tearing down an '89 5.0. I know very little of the history of this motor but it has a larger cam , stock heads and intake.
The heads were just rebuilt prior to me getting the car.
In looking at the top of the pistons, they have a large buildup of carbon. (I think). Dark / rough substance.

Would this be a result of the heads needing valve seals or another issue ?

Any input is appreciated.

[penceracing]

take a pic of them

[draggin50]

Valve seals and rings it sounds like....

[NXcoupe]

Could just be age and someone lugging it around rather than driving it like it was stolt. Also, if it has a larger than stock camshaft, it was probably running rich as a bitch, that would cause carbon and cause valve seals to croak.

[Rocket]

THANKS EVERYONE FOR THE INPUT. KNEW THE CAM WOULD MAKE THE MIX RICH- NEVER KNEW IT WOULD AFFECT THE SEALS.