5.3 Crank balancing question
 

I have a gen 3 5.3 and I'm putting gen 4 rods and pistons in it. To have the gen 3 crank rebalanced, it'll cost $300. A used gen 4 5.3 crank is $150. I'm thinking it would be cheaper to just swap in a gen 4 crank too and change the reluctor wheel to a 24t. That's assuming all of the gen 4 cranks are balanced the same, which they should be close because all of the pistons and rods weight the same from engine to engine. Thoughts?

All of the Gen4 crankshaft that were assembled into a 5.3L have near the same balance performed. (NOTE: there are exceptions where some pistons are lighter with smaller skirts and have a different balance performed).
Be warned... a Gen4 crankshaft from a 6.0L or 6.2L will not have a similar balance.

No matter which crankshaft you select, there should always be a re-balance performed.

Can you get away with finding a Gen4 5.3L crankshaft that matches and use it with out a re-balance... Yes, It is just not ideal.

Plenty of people have swapped to gen 4 rods without a rebalance and had zero problems. I really don't think it's worth it. If it were me I'd just run it.

True!

I can not count the amount of rotating assemblies that I have balanced. However generally the mass of the factory LSx connecting rods does not vary greatly... I'm sure many, many people here do this, an get away with perfectly fine.

That does not make it proper procedure for engine rebuilding.

Thanks for the replies! This engine is just a budget turbo build so "close enough" should work.

Can you post back later on and let us know your results and what you ended up doing? and the power your making and RPM. I'm in the same situation.

Not his results but my buddy's truck has a gen 3 6.0 that spun a rod bearing so we put a 4.8 crank and 4.8 gen 4 rods and pistons in it with no balancing. He runs 7k rpm and 20psi from an on3 88mm been that way for about a year and no problem.

Do you have the gen 3 rod and pistons you pulled out? If so just weigh it to see how much a difference it is vs your gen 4 rod and pistons to see how close you are.