Gm's offset rod ?
 

If your tear down a newer style ls stock motor and you measure the center of the pin to the piston skirt with a mic you see that their relationship is offset. Gm makes them This way to supposedly control the piston movement inside the bore when the rod is stroking up and down. What are the benefits of keeping this offset relationship when selecting a new set of pistons ? If you go buy a new set of slugs more than likely this offset will not be maintained. The piston will be centered to the rod. Is there any benefits. What is the reasoning behind this !

FYI, all after-market LS rods are centered, and traditional SBC are off-set. I am sure you knew that...just throwing it out there.

-Adam @ Callies

Almost all of the aftermarket pistons I've seen have some offset for the pin. IIRC, the whole purpose is to keep the piston from rocking back and forth and making a ton of noise when the engine is cold. The only ones I've seen that didn't were outdated or custom designs.

I must have had the exception. I bought two sets of aftermarket pistons and I measured and no offset rod. Needless to say the were very noisy on startup.

What brand and model number are these pistons ?

Dave

Wiseco and Diamonds are offset.

My Wiseco's are offset

My Racetec's are not offset and the motor sounded lke a diesel. They are on their way back to Racetec as I write this to see why.

Yeah non offset is a lil noisier usually. Even factory low clearance cast piston have offset. Wiseco and Diamond both send out their shelf pistons with an offset as notated by the dot or arrow that points to the front.