Re: What's wrong with running stock 400 sbc rods?
Couple reasons really. Number one.....It dont matter how long the rod is.....most any small block chevy STOCK rod(5.7 inches, 24 inches.....9 feet....whatever) they aint all that great for performance apps. They arent the safest pieces you can use. You can work on em and get em prepped to take a bit of a beating, I wont doubt that. But for the money invested in refurbishing stockers to do a good job.....your most of the way to a descent forged(like a scat for example...good stuff at a good price)......so..........might as well step up since your almost there! Same with heads for example. Spend 600 bucks on doing the best you can with stock smoggers....or spend 200 more on the vortecs your looking at that will end up much better in the end.
Another thing....longer rods tend to reduce the load on the bores a hair. So the longer you go(rod lenght), the better chance you have on releiving stress and taking away load from the bores.
Also, longer rods are said to be LESS sensitive to detonation. Longer rods dwell longer at top dead center and less at bottom dead center. The longer dwell time at TDC is said to ease up on the pinging factor(good thing))....but some of these things are kinda hard to test. Im not building two identical motors with different rod lengths and running them just as hard and just as long just to see which one wears the bores less or pings less. Fortunately, the load thing can be graphed out, and although the difference is very minimal, there is a difference so you can see it. The pinging thing....you just have to try it, but its said to work by many and Im sure someone out there smarter with more time and cash than me has tested it in order for this theory to have developed.
Lastly....longer rods(especially aftermarket with better profiling) often allow for an easier(and cheaper) internal balance job. This is also proven in a lot of situations.
In the end.....buy GOOD rods. Thats the most important thing. You will hardly notice some of the other things I mentiond...but you will know right away if you break a rod.