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I’m building a gen 3 5.3. It’s bored .020 over with flat top sealed power pistons with stock rods. Tsp stage 2 low lift cam. Is rebalancing needed or is my machinist tripping ? He told me it’s not necessary but from what I’ve researched it seems to be. Any help is appreciated it. It’s my first ls build and I would like it to be right. I’ve got a decent amount of money into it already.
I’m building a gen 3 5.3. It’s bored .020 over with flat top sealed power pistons with stock rods. Tsp stage 2 low lift cam. Is rebalancing needed or is my machinist tripping ? He told me it’s not necessary but from what I’ve researched it seems to be. Any help is appreciated it. It’s my first ls build and I would like it to be right. I’ve got a decent amount of money into it already.
From my experience, Sealed Power pistons are typically extremely close to the OEM pistons regarding weight, as SP strives to meet that benchmark in an attempt to keep the end user from rebalancing. Trust your builder here. If it was a problem, he would gladly balance the assembly and charge you more.
The reason a machinist will always recommend it, is because s/he won't want to deal with complaints about that it needed it butt didn't get done. (vibes) They wanna get paid up front to listen to the P&Ming.
That said, there's been about a billion "rebuilds" done with success, without it. It's more a question of uncertainty and risk than "need" as such, especially with a minor stock-ish kind of freshen-up deal like you're describing. Once you start buying into aftermarket cranks and rods though, you'd be a fool not to do it, however.
I like to fit a liter piston/pin WITHOUT engine rebalance in an LS engine.
The term "Overbalanced Engine" is good for rod-bearing life.
Your engine will have less vibration as the RPM increases.
What is your weight difference ?
I like to fit a liter piston/pin WITHOUT engine rebalance in an LS engine.
The term "Overbalanced Engine" is good for rod-bearing life.
Your engine will have less vibration as the RPM increases.
What is your weight difference ?
I’m not sure of the weight difference but the SP piston with pin says 568 gram +/-8 grams.
I have found a LOWER cost when a "liteweight" pin is used to replace a standard pin.
When the combined piston/pin cost IS often less than the Balince cost.
Ask him tomorrow the weight differences between the piston sets, and pick his brain as to why he doesn’t see the need to balance. Personally if it’s a performance build, I’m balancing no matter what. $250 (if no Mallory is needed, and I’m SURE you don’t need weight added) is not a big deal in this hobby, when it comes to peace of mind.
when a "liteweight" pin is used to replace a standard pin
Same here. I don't know all the ins & outs of LS motors in this area, butt the old SBC, there was a MUCH lighter pin you could use. Any reduction in reciprocating weight you can get is a win-win. (except that it will almost certainly require a re-balance)
I don’t have the oem pistons.
Try a junkyard. They might have a couple maybe.
the SP piston with pin says 568 gram +/-8 grams.
OK fine: see what the new scale you bought today says.
New OEM flat top 5.3L piston and 5.3L with 4cc valve relief pistons. Both standard bore and I believe with pins installed.
572 flat top Floating pin design
573 4cc valve relief Floating pin design
Last edited by 1FastBrick; Feb 3, 2025 at 12:22 AM.
The Cranks are slightly over balanced from the factory to take into account variations in manufacture runs. If you are with in 10 Grams, you should be fine.
As Che70velle has told you, you shouldn't need to have it balanced. It won't cause an issue for a stock rebuild.
If you want to have it balanced for the best possible results or for a performance build that's just fine.
New OEM flat top 5.3L piston and 5.3L with 4cc valve relief pistons. Both standard bore and I believe with pins installed.
572 flat top Floating pin design
573 4cc valve relief Floating pin design
those are weights for a standard bore piston though. Wouldn’t .020 over be a bit heavier ?
Ask him tomorrow the weight differences between the piston sets, and pick his brain as to why he doesn’t see the need to balance. Personally if it’s a performance build, I’m balancing no matter what. $250 (if no Mallory is needed, and I’m SURE you don’t need weight added) is not a big deal in this hobby, when it comes to peace of mind.
Ok I’ll see if I can give him a call
Last edited by stewy2115; Feb 3, 2025 at 03:43 PM.
I'm really surprised a machinist/engine builder would say balancing isn't needed. While you may get by without balancing that sounds like something a shade tree or "sloppy" type builder would say. Trust but verify everything seems to be the motto of every machinist I've met.
I'm really surprised a machinist/engine builder would say balancing isn't needed. While you may get by without balancing that sounds like something a shade tree or "sloppy" type builder would say. Trust but verify everything seems to be the motto of every machinist I've met.
He may not be wrong I'm just shocked to hear it come from a machinist or engine builder willing to put their reputation on the line by not verifying everything during an engine build.
those are weights for a standard bore piston though. Wouldn’t .020 over be a bit heavier ?
All depends on the casting. I have 2 buissness cards here that measure .025 put together to give you an idea of the thickness we are talking about.
Maybe the shape of the skirt is different, maybe the material composition is different. Perhaps the area around the pin boss is different. There is so many variables that could affect how much it weighs. The manufactures take that into account when they design a replacement part. They target the OE weight and compression height as close as they can so that when you do stock rebuild it doesn't cost money in extra weight or requiring a tune to adjust for the compression.
All depends on the casting. I have 2 buissness cards here that measure .025 put together to give you an idea of the thickness we are talking about.
Maybe the shape of the skirt is different, maybe the material composition is different. Perhaps the area around the pin boss is different. There is so many variables that could affect how much it weighs. The manufactures take that into account when they design a replacement part. They target the OE weight and compression height as close as they can so that when you do stock rebuild it doesn't cost money in extra weight or requiring a tune to adjust for the compression.
yeah that’s true. I think I’ve found a few things out. I found a forum that I think should be shared and you can kinda go off what it says weight wise. I also seen where on summit someone asked a similar question as I originally did regarding weight of those sealed power
pistons and here is what was answered by summit. Traditional counterweight crankshafts GM 5.3: 53lbs (weighed, out of engine with dished pistons) GM 5.7: 51lbs (weighed, drilled mains) GM 6.0: 52lbs (weighed) GM 7.0: 56lbs (4.000" stroke) GM LSA 56lbs (weighed, with 58 tooth Reluctor)
Manley Super Lightweight 46 - 48 lbs (4.000" or 4.100" stroke)
Callies Dragonslayer 4.000" stroke, bob unknown: 46-47 lbs 4.125" stroke, bob unknown: 47-48 lbs
Callies Magnum 4.000" stroke, 1750gr bob: 47 lbs (advertised) 3.625" stroke: 47 lbs (weighed, with billet Reluctor)
Callies Magnum XL 34 - 47 lbs (2.600" to 4.300" stroke, custom, advertised) 4.000" stroke, bob unknown: 43 lbs
Center counterweight crankshafts Callies Ultra Billet: 60lbs (ls7, with reluctor, advertised) Sonny Bryant ?
Rods Gen III LS1: 617 grams (6.098" for .945" dia pressed pin, weighed) Gen III LM7 606 grams (6.098" for .945" dia pressed pin, weighed) Gen IV: 640 grams (6.098" for .943" dia floating pin) GM LSA 692 grams (6.125", weighed) Eagle ESP 619 grams (6.125") Scat I-beam: 590 grams (6.125" for .927" dia floating pin, weighed) Scat H-beam Q lite: 565 grams (6.125" for .927" dia floating pin) Comp-Star H-Beam: 615 grams (6.125" for .927" dia floating pin) Comp-Star HD I beam 642 grams (6.125", 7/16 bolts, #CSC6125DS2A2AI) LS7: 465 grams (6.064" for .9252" dia floating pin, weighed) Lunati Pro-Mod: 667 grams (6.125", .927" dia floating pin, weighed) Lunati Pro Billet: 640 grams (6.125, 7/16 bolt, weighed) Carrillo Pro: 541 grams (6.125, with 3/8 WMW bolts installed, weighed)
Piston pins Gen III (.945" = pressed fit) OEM 5.3: 163 - 164 grams, (weighed) Speed Pro 4.8: 146 grams, (weighed, come with H855CP piston) Speed Pro 5.3: 149 grams, )weighed)
Gen IV (.943" = floating) LS2 147 grams (weighed) LS3 145 grams, (weighed) Wiseco #S785: 121 grams (weighed, 2.25" wide) JE #945-2250-15-51C: 105 grams (advertised, made for FSR pistons)
Other GM LS LSA: 146 grams (.940 piston pin, weighed) LS7: 105 grams (2.25" x .925", Wiseco #S761, weighed)
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Rebalance needed ? 
