[oldman]

IMO, the stock chevy rod is pretty strong, as with most OEM parts it is the bolt that is "weak". Even then say 6800 RPM bone stock bottom end is within the safe zone IMO. There are people that push the stock bottom end to 7200 RPM. So should you just change the bolts and be safe? dunno. I tossed around the idea as you have to change the bolts anyway (one time use). I decided on my build to go to aftermarket rods. Here is a picture of an aftermarket rod bold (ARP 2000, 220,000 PSI tensile) vs stock. Sure you could buy ARP rod bolts.

Here is a picture of the stock rod bolt, note that it is much thinner. Note the ARP bolt is tapered in the middle, this is where the stretch happens. The stock rod bolt will have a tendency to fail as head to shaft transition where the stress is along the very outside corner of the transition(or the thread to shaft transition) . The aftermarket bolt with thinner shaft (still way thicker than stock) has a much much larger head to shaft transition area. Nutshell I'm confident that the aftermarket rod bolt is good to any RPM my OHV street engine will be able to go even with my much bigger cam say 7300 RPM fuel cut, shift at 7100 RPM, peak HP at 6600 RPM.

diameter of stock shaft .328 (.0845" sq) diameter of aftermarket rod bolt .369 (.1069" sq). So about the 20% more area for identical mass rods. Let's ignore the better bolt design at the head, and assume one was going to use better ARP bolts with the stock rod. How much more RPM can one get out of a 20% stronger bolt? Let's say from grins that 7200 RPM would be a reasonable RPM to assume the stock rod with ARP bolts would hold for a period of time. Strees goes up with the square of RPM... so 20% stronger... yeilds 7900 RPM (assuming my Math is OK). Basically 20% stronger yeilds a 10% increase in RPM due to the sqauring of stress.

So I would assume my rod bots along with the aftermarket rod are good to go at 7300 to 7400 RPM, in fact, plenty of headroom.

Real nutshell, probably makes sense to just buy a new rods vs change bolts at this range:
Stage II up NA cams / heads
Stage I up FI cams..

Stage I cams and stock fuel cut at 7000 RPM, I would think the stock rod with ARP bolts would be fine.

I did stock weight aftermarket rods, IMO stage II FI, should do a much heavier rod / piston combo and rebalance. H beam rods are kind of thin at the stock weight aftermarket rod (IMO)....

Also IMO, even stage 1 FI will have issues with the stock rod itself (assume the bolt is change to ARP). powder steel rods just are not designed to hold the load of 850 engine HP. The failure at this point is NOT RPM related rod tensile failure, but compression force failure probably at the pin area or at the shoulder transition causing distortion on the big end and allowing the bearing to spin...

[Tim M]

If I had it torn down to that point, always aftermarket rods, but I like rpm so...

Additionally, if you are intending to install ARPs in place of the OEM rod bolts, believe one should have the rods resized to correct any distortion...further tilting the favor to the aftermarket...but I'm not a professional engine builder.