hey guys, in the middle of rebuilding my 94 12 valver. talked to the guys at cummins, and they said with the .5mm oversize pistons i'm going with, balancing isnt necessary. anyone concur??

 

My guess is they should know.... Fact is once an engine is balanced, if you change any part of the rotating assembly, it will not be in the correct balance. I know these things don't spin that high of rpm's. I just believe things should be done right the first time. That's another reason I don't like the idea of adding a dampner that weighs alot more than stock. Unless flywheel/flexplate and balancer/dampener are neutral balance...
A good engine balancing takes into account the amount of oil that can be carried with pistons/rods/bearings. I can't believe that an oversized piston wouldn't thro things outta balance.

 

The Cummins engine is internally balanced, rotating parts are balanced in rotation-crank, flywheel, harmonic balancer. Pistons and rods are balanced to the weight of each other and I think you will find that the weight between pistons is pretty close from the factory. Diesel engines are inframed all the time with piston/liner kits right out of the box, big pistons-big engines 800+ cu/inches cant remember it being a problem unless exceeding the rpm by a lot. PK

 

If I were you, do it right the first time, and get it balanced. You have the thing all apart, and for a few more $, you can get your truck to run like a sewing machine, just my opinion.

hope this helps

 

thanks guys, appretiate ur input

 

Cummins engines aren't "balanced" from the factory...

the individual components have a weight difference tolerance, but they aren't balanced to eachother on each engine.

unless you're going to be turning 5,000rpm, I don't really see it as necessary