When is balancing an engine required?

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Jan 20, 2015 | 06:25 PM

NTIMD8

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When is balancing an engine required?

Hi guys, I'm building up the bottom end of an LS6. Im using forged pistons which I bought used, forged 4340 connecting rods which I also bought used and using a stock ls6 crank shaft.

My understanding is there is no need to balance the FW (vehicle is an Automatic) or balancer.

Would I have to balance the crank since it is a stock crank or does balancing the crank also tell you what rod/piston set to put on what journal?

I weighed each piston and with the rings, pins and locks they all came in at 562g. I would assume since the rods are used they have also been balanced. I will weigh them when I get them in my hands.

Engine balancing is just something I know nothing about so info from people who know for sure would be greatly appreciated!!!

Jan 20, 2015 | 11:28 PM

Mercier

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Here is a thread that should be good reading for you. Plenty more on the subject if you search.

https://ls1tech.com/forums/generation-iii-internal-engine/1280524-how-rotating-assemblies-balanced.html

Good luck.

Jan 21, 2015 | 12:43 AM

KCS

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A crank is balanced to the rest of the rotating assembly (ie rods, pistons, bearings, etc). When you change the mass of the rotating assembly, the crank is no longer balanced.

Jan 21, 2015 | 05:35 AM

farmington

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any time you change rods, pistons, or crank you will need to rebalance UNLESS you are replacing with factory replacement parts.

Jan 21, 2015 | 05:41 AM

redtan

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The bottom end is balanced down to the gram in weight, so anytime you change any of the components by more than that you're gonna want to re-balance the whole thing.

Jan 21, 2015 | 07:28 AM

NTIMD8

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Thank everyone!

Okay so even if each of the new pistons + rods are all the exact same weight of each other I still need to get the crank balanced with the new pistons and rods because the new piston + Rod weights are different from the stock pistons plus rods wait, correct?

Last edited by NTIMD8; Jan 21, 2015 at 08:06 AM.

Jan 21, 2015 | 11:20 AM

redtan

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Quote:

Okay so even if each of the new pistons + rods are all the exact same weight of each other I still need to get the crank balanced with the new pistons and rods because the new piston + Rod weights are different from the stock pistons plus rods wait, correct?

Yes, because it's the fact that you changed overall weight that you have to balance not because each piston+rod combo weighs differently. I would sure hope that those two weigh the same across all 8...