Brutus wrote:Don't think a stock motor will ever see 7k , the lifters will bleed down plus the heads won't flow , not to mention the valves bouncin off there seats.

You had your head out in the cold or something Brutus?
I was talking about what the stock rods and cam will take. Not what a stock engine and cam etc will do.
Obviously he isn't going to rev it to 7.5K as it is. All I am doing is telling him to stop worrying about hitting 6K.
All you are doing Adam is making him worry about stuff he does not have to worry about at his level of performance.
If he has the springs that match that cam he has, he will probably be OK up to 6.5K. But, shifting at more like 5K as he is, he is not even using anything like the full power of the engine.
Rod bolt stress has to do with piston speed and weight.
Chrysler engineers designed the rods/bolts to take 6.5K for short periods of time with the stock pistons easy.
If you are hitting 6.5K a dozen times every weekend then yes they may well eventually fail.
But a few times, once or twice a year, isn't going to hurt them.
Another factor is stroke length. The longer the stroke and the shorter the rod, the faster the piston speed. And the faster the piston has to change direction.
This, as you can imagine stresses the big end and rod bolts MUCH more.
Lighter pistons than stock however will take some of the strain off the rods. So when you fit lighter aftermarket pistons you are in effect also giving the bottom end much less work to do.
One more factor is balance. The better the balance job on the engine, the more you can rev it. This is because a smooth engine puts less stress on the parts and allows them to rotate faster with less stress.