With my all iron SBC I like to change rods & bolts at about 75-80 runs. Alto because of the timing between races, last time I changed them at 100 runs. Now these are for my 10,000 rpm alky motor. If I was running lower rpm, lower HP or lower compression ratio, I could get more runs on the alum rods. i know one JF team that killed a motor with tie steel rods after around 100 runs, because he thought they would not break, Wrong, steel rods break too after too many runs.
Jon