I just purchased a .030 over 351w short block from Ford Motorsport. All the pistons have numbers and an arrow etched into the top. All the arrows point towards the front of the engine and a cast in mark on the piston except number 8. On 8, the arrow points towards the rear of the block but the cast in mark is towards the front as on the other pistons. Is it safe to assume the etchings are wrong and go with the cast in mark? There are no obvious indicators on the pistons other than the cast in mark.

 

"Marty" at Ford racing says " You should go by the casting mark". The wrist pin is slightly offset to reduce pressure on the side wall. I'm still not to sure. Does anyone know if the offset created during casting or machining? I would imagine the printed orientation marks are created after the piston is machined. I am going to try & measure the offset between the cylinder wall and connecting rod. I want to avoid disassembly if possible.

 

The offset is created during the machining process. Offset goes toward thrust ( passenger ) side. It is strange that there is a machined/ engraved mark along with the cast dimple/notch. I would turn it upside down and look at the pistons from the bottom to compare the offset ( you may have to look pretty close ro see it ).