As far as the pressed fit vs floating pins, there's also a manufacturing concern... Each process has it's difficulties, it's what the assembly plant is better at managing... And the grass is always greener on the other side of the fence...
Either way, the wrist pin can rotate in the piston bore and also slide side-to-side axially within a limited range so it doesn't go outside the piston and score the cylinder... So it's still functional...
On a floating pin, the clips keep the pin from going into the cylinder wall... On a press fit pin, the rod is anchored to the pin and the pin can rotate in the piston bore, and also slide side-to-side in the range allowed by the clearance between the width of the rod and ears of the piston... On a press fit pin, there is an interference fit between the rod bore and wrist pin... On a floating pin, there is a clearance fit between the rod bore and the wrist pin... In both cases, there is a clearance fit between the piston pin bores and the wrist pin which allows the pin to rotate and move axially...
The problems for the assembly plant with the press fit rods are the heater to heat the rod to allow the piston to be pinned requires some attention to keep the temperature proper... Too cold and the pins will hang up and won't pin, and too hot and you burn the rod and weaken it... You want to run the rods at 450° minimum to allow the bores to expand enough to run the pin in... They will turn a "straw" color (light brown) at around 500° - 517° and are still ok to use. You usually burn the rod around 520°-525° F and it turns blue, which allows the micro-structure in the metal of the rod to relax and weaken it - those should be scrapped... If you load too many rods at once, they do not get hot enough because the heater setting is based on how much mass is passing through it at a given time... The first few rods coming out of the heater when the process is started are usually too hot/blue because of the empty space in front of them where there were no rods to soak up some of the heat and the last few out of the heater turn blue because there are empty spaces behind it and they are now overheated... So every time you run a batch of rods through the heater, you have to set the first and last few aside to be scrapped... If there are hiccups in middle of the process and the rods sit too long in the heater, they burn... You have to keep the process going.... But when you get the process running as steady state, you can bang them out one after another...
The problems with floating rods is the wrist pin clips... If you miss one, then the piston pin will walk and score the cylinder bore... When you have to pin hundreds of rods per hour, it's difficult to keep one from missing a clip... Sometimes the clip doesn't properly seat in it's groove and will spring/fly out of the piston after it's done, even though it passes inspection after getting installed... One or two of these happen once in a while... It's easy for us building one engine at a time in our garage to double check, but on the assembly line, you have to keep things moving and don't have time to finger-f*ck every one...
