I guess I have a whole lot more faith in the OEM C7AE-B rods (or other beefy part numbers) than some folks do. I am not a "real" engineer, but I am a pretty good hillbilly shithouse engineer. That is a trademarked term, by the way, ha ha. Back when aftermarket rods were not legal in Stock and Super Stock, we....and many others........did figure out how to make the rods live. I absolutely agree that RPM is much harder on the rods than power alone, and really high compression ratios stress things more also. Most "windowed" FE blocks are from RPM related failures, but not from BROKEN rods initially. First, they spun the bearing, and then the cap came off, and then it went through the side. My opinion is that in the vast majority of rod failures, the rod broke after it slapped around on stuff a few rounds after the bolts failed and the cap flew off. I have seen the beams bent double at times, that did not break.
The Lemans rods became junk when the dowels got loose, and the cap would not repeat the same place twice. Many guys just bolted them right in there, unround, with bad clearance issues, and never knew it. The 3/8 "nut and bolt" became the rod of choice, for the extra meat that remained around the housing bore. When we learned how to prep the big end of the rod to compensate for the flex, and MUCH better fasteners came along, the rod and bearing troubles really became a non-issue. If the housing bore is not fixed right, the bearing, which is too narrow for it's diameter, will spin in the bore, hence starting the snowball effect that ends up a hole in the pan rail. While I am sure there have been cases where a rod beam did fail, the vast majority of stock FE rod problems begin with the big-end compromised.
I grew up at racetracks, watching FE's with stock rods turning 8K repeatedly, and if prepped properly, they rarely had problems. If prepped "well" but wrong, they would not make it through one weekend. When I do an engine these days with OEM rods, they get the 1978 "Super Stocker" prep job, along with ARP bolts. My gut tells me that I would not worry about the rods breaking with a blower, below 6500 rpm, if it had even 600-700 HP. I would want to polish the beams, make sure there are no stress risers, and mag them, or even X-ray them, and shot peen them. We have a few places in Chattanooga that used to do metal parts prep work for the foundries and for CE that will do some of that stuff for surprisingly low costs. I send six or eight sets of rods at a time, and then shelf them, and the per set cost is less. Then, doing the big-end and adding bolts can be done as needed. Clevite used to make a bearing # 952-P that also helped. I find the King bearing will carry the load better these days than the Clevite or the F-M offerings. Both the rod journal and the rod big-end bore need to have VERY minimal taper...........less than the bearing books profess.........because the FE rod bearing is absolutely too narrow when loaded heavily, for anything to be out of wack.
The big end needs exaggerated eccentricity at the parting line, and very tight vertical crush. There are several ways to get there, but that is how they will survive. Scary tight vertical bearing clearance, and scary loose at the part-line. The bearings will be beautiful upon teardown. I think it would be cool to do an FE with a light box-style forged piston, properly prepped OEM internals, and 8-10 psi boost. If I live long enough to do it, I have plans to play with that myself. I think the 390 crank, or even a 361 steel unit (low cost core) with the snout and tail fixed would be really durable. 3-webs, studded mains, and head studs and Cometic head gaskets. Should run a LONG time. Low cam lift, .500-ish, with a valve job for that idea, and a head that can be prepped to compliment the cam.................duration depending on cubes, wide separation, really good exhaust "blowdown" and good follow-up exhaust flow. Sweet for the street. JMO.
