Eagle wiseco weight question

[94talontd]

So I got my new Eagle rods and Wiseco pistons today, what Im curious about is I weighed them and two pistons weighed exactly the same (to .1 gram), but the next one was .7 grams off and the last one was 1.5 grams off. Next, I weighed my rods and again 2 were exactly the same but one was .9 grams off then the last was .7 grams off. Is this gonna couse any balancing issues? I know the weight is miniscule and it equates to less than a 1/2 percent difference in weight(on both the pistons and the rods each) but I can't seem to get it off of my mind. This will be my first engine build so I just have no idea what is acceptable. Thanks in advance and your input is appreciated.

 

[2qik4u]

the weight isue can easily be solved by taking the lightest one and removing weight from the others till they all match. i use die grinder with a carbide cutter but a buddy of mine uses his drill press with a nice sharp brand new drill bit and remove a tiny tiny bit of metal till each weigh the same. then balance wont be an issue!

 

[94talontd]

I never thought about that,it doesn't sound too difficult either. Thanks for the info. Any suggestions on where to take the weight off?

 

[TunaTalon]

Rod weights need to be matched top end to top end and bottom end to bottom end.

The top one third of the rod is reciprocating mass and the bottom two thirds of the rod is rotating mass. Lower reciprocating mass means lower stress on the bearings, and less vibration from second order harmonics.

 

[BogusSVO]

here you go.......
http://www.dsmtuners.com/forums/cylinder-head-short-block/342138-how-fix-balance-hang-pistons.html

then you should have your pressure plate, flywheel, crank, and harmonic balancer all spun balanced and you will have a good smooth running engine

 

[2qik4u]

+1 on rotationally balancing the flywheel and such!!!
+1 on the how to link!!!!!!
+1 on the rod end weights!!!!

good info!!!!

 

[94talontd]

So I decided today to quit bein a cheapa** today and took my rods, pistons, and crank to a reputable machine shop in my area to have them balanced. Theyre chargin me $100 for this so I didn't think it was all that expensive. I have an automatic car so would this be good enough balancing?

 

[TunaTalon]

At any given RPM the effects of engine imbalance are the same for manual or automatic transmission cars. However, the higher the RPM the more important it is to have a balanced engine.

As long as you're using the stock TCU your car will up shift at 7000 RPM at WOT. With a manual higher RPM's are likely.

In any event the imbalance forces from second order imbalance will swamp the static imbalance discussed here.