Balancing

[jaluhn83]

For those that balanced these engines, how did you do the rods? What kind of weight variance were you seeing? My pistons were with ~3 grams of each other out of the box and are now within ~1, but the rods I just got thanks to riotwarior are as much as 20 grams apart.

It looks like you can take metal off the bottom of the rod caps and the side of the small end flat, but my concern is that I don't have a good way to measure end to end balance and that seems pretty critical.

 

[racer30]

I Lightened My NA rods by removing .220 from the rod cap weight. Then using a rod scale jig I balanced the rods to within 1 gram. Then I removed 20 grams from the little end and rebalanced them again. PM me and I will give you the code to my fliker account and you can see my pics and read my notes. I'm Not quite ready to start my thread on my build, But a few people have my code to see my pics and info.

 

[riotwarrior]

Why are you yourself attempting to balance the engine? Can you balance the rotating mass? If not then this only does a halff assed job sorry to say.

All reciprocating mass and rotating mass must be balanced as a whole. I don't understand how what you are doing will affect engine balance other than even out reciprocating weight. That still leaves the crank, harmonic and flywheel/clutch assembly to balance.

JM2CW

Al

 

[jaluhn83]

Hmmm, good point. Mainly I'm trying to even out the reciprocating weight on the assumption that the rotating mass is reasonably well balanced already. But maybe I'll look into getting it properly balanced.

No real reason to think there's a problem with it the way it is, but I figure it can't hurt anything to make sure things are even, as long as I don't take so much off to cause strength problem or mess up the higher order balancing of the assembly.

 

[riotwarrior]

Hmmm, good point. Mainly I'm trying to even out the reciprocating weight on the assumption that the rotating mass is reasonably well balanced already. But maybe I'll look into getting it properly balanced.

No real reason to think there's a problem with it the way it is, but I figure it can't hurt anything to make sure things are even, as long as I don't take so much off to cause strength problem or mess up the higher order balancing of the assembly.

I assure you that even if balanced....meaning you balancing rods, and pistons...you did include the wrist pins, locks and rings properly gapped when you balanced pistons right? the chances of that crank matching all your work...pretty damn slim IMHO.

Remember those rings need to be gapped per bore, then you throw those with each piston for each bore with the wrist pin and locks on the scale and THEN balance that mass. cause if you didn't do that, they are likely off already

Thus taking all your handy work into a machine shop and going

PLEASE balance makes life simple, but again you must do all the pre work, checking out bearing clearances oh ya don't forget rod bearings when doing balance...DOH there is a ton of work to blue print and balance an engine, trust me I know and don't even ask how or why, I've had to write down so damn many bearing clearances and dimensions of rods, ring gaps, and so forth and its not funny anymore....

Basically it's a ton of work but well worth that investment in time and effort bar none!

JM2CW