changing rods/rod weight

First off, great site Will.

I have a question and would appreciate some of your thoughts. I am changing rods, but I am not sure if I should re-balance the crank because of this. At this point, I haven't weighed the rods, so I don't know the difference between the old and new brand rods. Should I spend the money on a scale and worry about a 0.1 gram difference, or should I just throw the rods in and send it down the track?

Thanks.

 

Send it.

 

Rods are a different brand. I have NOT weighed anything, so I really don't know how much of a difference there is. Just wondering what others think about it.

 

Send it.

 

what Randy said- "Send It" Don't fool yourself that everything is in balance in a blown hemi- oil does funny things!

 

Thanks guys, makes sense to me. I'll throw in the new rods and won't worry about it.

 

I would weigh the new combination and the next time you order a crank use your new numbers if they happen to be different. Alcohol and fuel teams constantly cycle rods and pistons, run to run. It's not necessary to weigh each piston and rod out of every box because it's just one more thing to make you nervous.

If you've made a significant change like bore size or a change in pin diameters I would be more concerned. One school of thought says it's OK to run a crank balanced for a larger bob weight than you actually have, but never run a crank balanced for a smaller bob weight than you actually run. I like to keep it plus or minus just a few grams which is typical.

FYI: I have always been a real fanatic on little details like balance and bob weight and even discussed it with a major supplier of stuff we run several years ago. His opinion was that with a blower I was wasting my time worrying about it. His comment was to get an initial bob weight, order the crank based on that bob weight and don't sweat the +/- that will happen when replacing pistons and rods as often as we do.

Good luck.