I'm a newb to engine building, and I just got this 4 bolt main with brand new federal mogul forged pistons. There are write pins installed in the pistons but u can slide them from side to side... I thought there were supposed to stay put?? I know this is prolly a retarded question, but I"m just concerned... Like 7 of the 8 pistons' wrist pins can slide, one cant... I mean, their brand new, literally in the box... So nothing can be wrong with them... I dunno, lemme know! Thanks!

 

Are they set up for a floating pin? If so then they use retainers to keep the pin in place.

 

I don't have any clue... Where would these retainer pins go and how much do they cost? Someone's helping me with the build and I just haven't asked him yet.. If u gimme a minute I can prolly post a picture of the piston.

 

here

 

they are supposed to slide. When you press the rod onto the pin, the rod holds the pin inside the piston.

Eric

 

If you have floating pin pistons, there will be a bronze bushing in the pin bore on the top end of the rod. If there is, then the pins should be held in place by clips that fit into the tiny grooves in the piston on either side of the pin.
If you don't see any bushings in the rods and the pins slide, something's defective.
The clips are supposed to come with the pistons, but if they're used pistons then they should get new clips anyhow.

 

the pin is pressed on the rod and floats on the piston or the small end of the rod is bushed and the pin floats on the rod and snap rings or spire locks keep it in place on the piston.