I recently ordered a set of Callies Compstar 5.7" h-beam rods for a 355 I'm building. I never checked the pin bore diameter because I was unaware that they came in .927" and .928" (I thought they cam in .927" only).

Now I am stuck with a set of rods that are meant for .928" pins (floating style).
However, I am having a great deal of difficultly finding a set of pistons that have .928" pin diameter.

What are my options? Can I just use a set of .927" pins/pistons on my .928" rods?

 

They're meant for use w floating pins & pistons w retainers.

THINK about it... "floating" requires some clearance. That's why the extra .001".

Just get that type of pistons.

 

Wrist pin spec: 0.0006 - 0.0008" in piston, 0.0008 - 0.0010" in rod for full floating pin.

 

So a .927" pin will work fine behind a .928" rod?

 

Yup

Standard operating procedure

 

What Sofa said. The RODS are either designed to work in a full-floating application (and have .928" small end so the pin can slide through it) or press-fit application (and have .927" small end so it will "capture" the pin when the shop presses the assembly together).

So what you need are a set of pistons that are designed to work with full-floating pins. Such pistons usually utilize spiro-lock grooves on each end of the pin bore. Pistons designed to work in a press-fit application wont work with those rods- there would be nothing to retain the pin.

Full-floating application pistons can always be used in a press-fit applciation, but not vice-versa. It's a question of what's retaining the pin- either the rod does (.927" small end rods that grab onto the pin tightly) or the piston does (if it has grooves for spiro-locks or clips built into it).

Think about it a while and it'll make sense.

The nice thing about full-floating pins isn't just that they work well in high stress applications, but also that you can put the pistons on and off the rods by yourself. No need to take everything to a machine shop to have them press the pins on and off for you!

 

Thanks for clearing things up. I have only dealt with pressed in pins but I had some understand for how floating pins worked.