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Is this really how they balance the rods in a 350?

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Old 05-17-2018, 07:26 AM   #1  
LenWoodruff
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Default Is this really how they balance the rods in a 350?

These are the rods that came out of my L82 350. Do they really balance the rods by grinding the sides and the top like this?




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Old 05-17-2018, 08:02 AM   #2  
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The top, yes. There's also a pad on the cap that can be ground.

Sometimes the flashing on the sides is ground off, then polished.
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Old 05-17-2018, 08:30 AM   #3  
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Kind of some would call removing all the flashing typically shot peening afterwards as " race prepping" or lightening. There are balance pads on both ends of the older oem rods. Material is removed from either or both pads to balance. Removing parting line flashing would be considered lightening by an inspector. There builders who look for rods with the smallest pads because the beam would more material. The factory does a pretty good job of matching sets of rods. When flashing and pads are removed rods will need to balanced.
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Old 05-17-2018, 10:00 AM   #4  
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If by "they" you mean the GM engine plant, then my answer would be no.

If by "they" you mean somebody rebuilding the engine then my answer would be that a rough grinding like that is not normally done, but I could easily see someone doing it that way anyways. You don't want it that way because any rough edge left on the rod could potentially cause the start of a crack.
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Old 05-17-2018, 10:09 AM   #5  
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From what I know, any grinding off the flash/polishing/shot blasting the beams needs to be done before any balancing work is done. Those operations are to eliminate stress concentrations that could otherwise begin a fracture.

For balancing- first, the small end weights are checked while the big ends are supported like a fulcrum. The lightest small end is used as a target weight to be matched to all the others by metal removal on the top pad of the heavier rods. Once the small ends weights are matched, the whole rod is weighed and the lowest rod weight becomes the target for the rest of the rods. Metal removal then typically comes from the big end pads on the rods that are not the lightest one.

Pistons/pins are all weight matched and the crank bob weights are calculated before the metal gets removed from the crankshaft weights.
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Old 05-17-2018, 01:38 PM   #6  
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Go watch Vortec pros video. This is the first of 3 on his big block build involving the rods.

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Old 05-17-2018, 02:39 PM   #7  
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The low cost of better quality aftermarket rods justifies using aftermarket rods and just trashing the stock original rods. I shopped new rods and rod reconditioning machine work pricing. Once you include the price of better rod bolts the new rods are within $20 of reconditioned rods doing a lot of the work yourself.

Buy new and be happy.
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Old 05-17-2018, 03:31 PM   #8  
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Quote:
Originally Posted by lionelhutz View Post
If by "they" you mean the GM engine plant, then my answer would be no.

If by "they" you mean somebody rebuilding the engine then my answer would be that a rough grinding like that is not normally done, but I could easily see someone doing it that way anyways. You don't want it that way because any rough edge left on the rod could potentially cause the start of a crack.
Thanks. I thought it was poor craftsmanship which would lead to something else down the road.
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Old 05-17-2018, 03:33 PM   #9  
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Quote:
Originally Posted by cardo0 View Post
The low cost of better quality aftermarket rods justifies using aftermarket rods and just trashing the stock original rods. I shopped new rods and rod reconditioning machine work pricing. Once you include the price of better rod bolts the new rods are within $20 of reconditioned rods doing a lot of the work yourself.

Buy new and be happy.
Thanks. I am buying news rods since the machine shop swap these in place of my shot peened "Pink" rods from the factory.
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Old 05-17-2018, 04:36 PM   #10  
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Quote:
Originally Posted by LenWoodruff View Post
Thanks. I am buying news rods since the machine shop swap these in place of my shot peened "Pink" rods from the factory.
sounds like you need a new machine shop...and get money for your old rods.
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Old 05-17-2018, 05:22 PM   #11  
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Quote:
Originally Posted by Sleazy Rider View Post
sounds like you need a new machine shop...and get money for your old rods.
Thanks. Working on that now.
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Old 05-17-2018, 05:50 PM   #12  
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Quote:
Originally Posted by cardo0 View Post
The low cost of better quality aftermarket rods justifies using aftermarket rods and just trashing the stock original rods. I shopped new rods and rod reconditioning machine work pricing. Once you include the price of better rod bolts the new rods are within $20 of reconditioned rods doing a lot of the work yourself.

Buy new and be happy.
I am buying new and I will be happy.
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Old 05-17-2018, 09:26 PM   #13  
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Look at Scat. They make some nice rods for the price.
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Old 05-17-2018, 09:30 PM   #14  
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Quote:
Originally Posted by Sigforty View Post
Look at Scat. They make some nice rods for the price.
Scat are the ones we will be using.
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