Re: Longer rods
The thermodynamic Otto cycle burning gasoline is a very abrupt way of converting chemical energy into mechanical power (not a very efficient way either, which is why Diesel was able to improve upon it). The gas burns very quickly. Which results in a very large pressure spike at the top of the stroke making for a light yet powerful power plant. Great for air planes made out of canvas and a prayer and for moving the old horse drawn wagon.
By keeping the piston at the top of the bore longer with a longer stroke you can exert more leverage on the crank shaft. So early engines that were made by hand in a work shop had a small bore and a long stroke to try and capture the energy before it leaked away. They were closer to an antique John Deere putt, putt two cylinder engine that reved to only 1,600 RPM, than a Formula One race car engine that spins to 17,000 RPM.
Today we hone the bore with a deck plate holding dimensions to the fourth decimal place, and have a choice of five different ring faces for piston rings that are ground so flat that there is no break in period.
What hasn't changed is the fuel we burn. We are back to burning the same swill that was available before WWII in octane quality, yet our engines are making more power thanks to improvements in design and manufacturing. Can we improve on the design by using a longer rod to hold the piston at TDC longer a micro second longer than a shorter rod would? To me for a new rod I was going to buy any way, buying a longer length is a no brainer as it can't hurt. I like the reduced piston weight for the reduction in rotating mass that allows a motor to rev higher and faster.
But that is me. I generally do not use any Chevy parts to build a Chevy motor. New JE pistons, or from Mahl or Diamond, rods and crank from Callies, and block from Dart heads from whoever has the best head when I screw it together (technology changes every six months now). Cam and solid roller lifters are no where near stock. Intake from Edelbrock or Dart or AFR, Carb from Quick Fuel, Distributor from MSD and the bolts to screw it all together from ARP. I use an SFI front damper (usually ATI) and the two piece cast timing cover behind that seals to an aftermarket oil pan and matching oil pump pick-up. I might use a reproduction Chevy displacement and rated horsepower decal for the air cleaner that is often the only Chevy part on the car.