does it really matter? what size is better and why?
I dont want to buy the worng one and then have to buy a different one..

just wanna do this once!

thanks guys and I hate to have so many questions.

 

do you have an internally balanced crank? i'd go with the larger diameter

 

I'll second ede's recommendation. The damper is one place where bigger is better.

 

why is the damper better if larger? yeah its internally balanced....but why the larger versus the other? some people run smaller in their 383 or larger displacement motors....I do want a larger but I have a change to get a smaller 6.25 ATI..

thanks guys!

 

The larger damper will be more efficient in damping crank vibrations. Crank vibration can actually affect cam timing, which also affects ignition timing, so damping them out contributes to more power gain than the smaller damper's lower rotating inertia will provide. It also makes for longer crank life.

This is one time when a good deal on a smaller damper probably isn't.