Anyone have any opinions on which of those rods is superior?

 

The SIR rods are rebuildable, the PM are not!

 

its normally a rod bolt or loss of oil flow (which is often associated with a bolt having insufficient preload/torque). Second important factor is the rod weight.. and im pretty sure SIRs are lighter than the 600+ gram factory rods.


Find a rod that uses a cap screw type fastener (and use bolt stretch for establishing preload during installation) as opposed to a bolt/nut and all other issues will solve themselves.

PS. i think the ^rebuildable is kind of an oversimplification. The common thing now is to bore the big-end to approx .002+ oversized and use a thicker bearing.

 

Not to argue a whole bunch, but the factor SBC PM rods made after '94 are machined at the parting lines, so they CAN be resized...

Still, while they are good factory rods, there are better choices out there if you're planning for replacements. You'll have to go through all the balancing anyway, so you might as well start with a lighter, stronger con rod.

 

Vader,
So for a lighter, stronger rod would the SIR be the wise choice?

 

I used the sir rod in my 383. Building a 406 for my brother now, we bought scat pro I beam rods for it. They have cap screw type bolts and guide dowls. I wish I would have used them myself. Since eagle raised there price, those scat pros don't cost much more. They claim they are good to 650/700 hp.