I've got a build I'm assembly for a friend. He took his block, crank, rods, pistons and harmonic balancer to a machine shop. He didn't have his lightened flywheel or clutch yet, so the machine shop balanced the rotating assembly with just the harmonic balancer. Can the rotating assembly be balanced correctly without the flywheel? I know the flywheels are internally balanced but won't the front to back weight be affected by not having the flywheel and clutch attached?
The machinist I usually go to always ask for the flywheel, clutch assembly, rings and bearings when he balances my assemblies.

 

As long as the flywheel has been balanced it should be fine.

 

Ok, I think I remember now, Honda's are internally balanced, therefore flywheels don't affect the balancing process right?

 

Does front to back weight even come into play? If that is the case than the flywheel end of any engine would most likely be a good deal heavier.

I've always been curious of how they go about balancing a IL-4. My old machinist told me it is somewhat eaiser than a V6/V8 and that bobweights aren't used. Can anyone elaborate?

 

No bobweights on I-4 cause the rods and pistons don't rotate on the same planes as a V6/V8. The bobweights offset the reciprocating weight of the pistons and rods if I recall correctly. My machinist matches the pistons to +/- .5 grams, then the rod's big ends, then the rod's small ends.
For grocerry getters, +/- 1 gram is acceptable.

 

I'm still fuzzy on the concept. I guess I just don't understand why the weight of the pistons and rods isn't necessary when balancing the crank. I know one of the major differences on a V8 crank is that there are 4 crank pin angles @90* angles. (not sure if that's the right terminology) Where on a I-4 there are only 2 180* apart. Correct? But then there are also flat plane V8s. They use a crank similar to a I-4, would they share the same balancing characteristics as an I-4. Found a good website that shows different types of crankshafts if anyone is interested. Crankshaft Designs That's where I got most of the info from.

 

yes it is a good idea to balance the damper, flywheel and clutch along w/ the crankshaft. together or seperate, either is fine.

balance the rods/pistons to match by weight

good aftermarket rods/pistons are usually dead on and wont need adjustment.

i have found brand new oem honda dampers to be out of balance, always a good idea to check them.

 

I remember reading that link a while back, but couldn't remember the link when I was recently looking for it. Thanks for posting that up.