Help me please!!!!!

[motor_slut]

I think most pistons have a small arow stamped on them indicating "front" as in front of engine, too.......

Some are stamped to indicate the Magneto side too. Either way the ring pins and thus the ring gaps should always line up on the intake side.

 

[markf419]

They hit if you put them in upside down.

If the valves have a bevel on their edge like Cats, they may have been in upside down(backwards)
Flip the valves over and crank it over by hand (w/plug wires removed) and ck clearance.