I know that floating wrist pins ar held in by C clips, but how are pressed pins held in? Which is better to use in a performance engine? Or do they not make a difference

 

Floating pins are held in by clips... you are correct. They are intended to have less friction on the pin itself. Pressed pins are only held in by friction. You have to press them out and if you've ever tested one out of the engine... when cold they are very stiff.

All performance engines use floating pins to reduce friction. It is a better choice. Factories don't normally do that because that increases the labor costs. It is cheaper to have a machine press one in.

 

Pressed pins are pressed onto the rod, therefore the sideways travel of the pin in the piston is limited. Full floating pins also float on the rod, so the clips are needed to keep the pins from sliding into the side of the cylinder wall.

 

Spiro-Loks