Engine Balance

BigYellowIron

BigYellowIron

Diesel Tech
Joined
Aug 22, 2007
Messages
1,400
Im Going to play dumb for a little bit.

What is the process of balancing a Inline 6 engine rotating assemble?

I can find all kinds of info on V blocks but none on I6.

Can anyone share the process?

Adam
 
Pretty simple, atleast if it's a b series cummins, the crank gets neutral balanced, the rods and pistons get a weight adjustment so they are all the same.
 
Anyone know the specifics they are out of balance?

I weighed my pistons on a food scale, because it was what I had, just to see. They was all within a gram according to that scale.
 
Over 40 grams out and you'll start to feel it. Most are less than 30 out.
 
BigYellowIron said:
Anyone know the specifics they are out of balance?

I weighed my pistons on a food scale, because it was what I had, just to see. They was all within a gram according to that scale.
Click to expand...

Cummins holds pretty tight tolerances...

don't think in terms of grams, think in terms of percentage of weight... what was the average weight of your pistons?
 
My guy balances the crank, dampener, and flex plate/flywheel. Then averages the weight of the pistons, rings, clips, pins, rods, and bearings.
 
My crank was spin balanced and was 39 grams off. I had it done about 4 years ago and unfortuanately the guy is out of business now.
 
that would make sense in my mind.... especially in a high RPM app.
 
ok heres a dumb question is a counter weighted crank the same a balanced crank whats does the counter weighted one help with
 
On the high rpm alcohol tractor 6 cyls. they add alot of counter weight. A buddies 360 inch JD bent the crank twice before they got the right guy to balance it. This is with light pistons and aluminum rods. Bent around 4 thousands both times. When they added more weight it hasn't bent since at near 7000 rpm's. This is a diesel crank he runs. I don't know if overbalance pertains to the cummins.
 
Balance question to add here...

My old build that only lasted 2500 miles was balanced (crank, dampner, rods, old pistons)....The rods were lightened and balanced in weight also...Crank was balanced by itself as well I believe.

With this new build I just assembled using the same crank and rods in their same location....I just didn't weigh each monotherm to see if they were close....I assume if there not too far off, I should still be pretty well balanced..?
 
highoutputc said:
ok heres a dumb question is a counter weighted crank the same a balanced crank whats does the counter weighted one help with
Click to expand...

Hurley said:
^unless I dont know, all cranks are counterweighted
Click to expand...

Yes crankshafts are already counterweighted, but if a crank is referred to as "counterweighted" it means it has had additional weights added to it. It is poor language usage, I know.
 
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