I do not remember if when I had my engine parts at the machine shop if they balanced the assembly. I am buying an OE balancer from jegs and do not know if I get one for and externally balanced engine if it would hurt?

What is your engine?

Call the shop and ask them if they balanced the rotating assembly, of look at your bill and see if you paid for it.

I'm taking that if you are looking at an externally balanced balancer that you have a 400 or maybe a 383 ?

In your signature it says you have a 350 in a your 1980 Camaro. If it's still a 350 you need a neutral-balanced dampener, period. External balance dampeners are for 383 stroker motors, 400s, etc. that are most commonly external balanced. But no 350 ever used an externally balanced dampener.

As ZS10 said, "Call the shop and ask them if they balanced the rotating assembly, or look at your bill and see if you paid for it.

I just had my rotating assembly balanced. I'm building a 385 stroker (4.040" bore x 3.750" stroke). I'm using 6 inch rods so I could have it internally balanced. The Scat rods I bought all weighed the same. The machine shop needed my crank and one complete piston and rod set up which included a piston, a rod, a wrist pin, both wrist pin clips, a full set of rings, a spacer ring and both rod bearings.

They told me they didn't need my harmonic balancer and flexplate because it was being internally balanced and my harmonic balancer and flexplate are neutral balanced.

They said if I went with an externally balanced set up, they would have needed everything I brought them plus my harmonic balancer and flexplate.

If your motor is an externally balanced motor like stock SBC 400's are and most 383 stroker set ups, you're going to need to have your new balancer balanced with the rest of your rotating assembly. If you're building a 350 or another motor that's internally balanced you can buy a new balancer and put it on without it needing to be balanced with your rotating assembly.

standard 355 with stock crank and rods. I had the engine work done a few years ago and the shop is closed. I will have to look to for the paper work, I doubt I have it because it was when I worked as a mechanic at the dealership and I sent it through them. I could use my original if need be anyway it is still good. The pistons did not add that much more weight than stock.

I'm using 6 inch rods so I could have it internally balanced. The Scat rods I bought all weighed the same.

its not the length of the rods or that they weigh all the same that makes it internally balanced...i can weight match the rods in a stock 400 and it will still need to be externally balanced.

also,, when i balance a neutral balance setup like a 350,, i still recommend having the damper and flexplate, because after i get the balance in there without the damper and flexplate,, i mount up the damper and flexplate and match those to the crank. they become one.
it'll be "close enough",, but,, just because it's said they are neutral balanced,, doesn't mean they're spot on every time. i still check and correct at the damper and flexplate with them mounted up if needed. just my way, but it keeps things right after getting the crank right. hope it helps.
andy

its not the length of the rods or that they weigh all the same that makes it internally balanced...i can weight match the rods in a stock 400 and it will still need to be externally balanced.

It's my understanding that using 6 inch or longer rods with the 3.750" stroke (400) crank leaves more material on the crank so they can balance it internally therefore only requiring a neutral harmonic balancer and flexplate. The compression height on the piston puts the wrist pin in the "oil ring groove" requiring the use of a spacer ring. No biggy though.

Pretty much everyone makes internally balanced cranks for the SBC 400 (3.750" stroke with 2.650" mains) now. My 385 stroker set up uses 6 inch rods with 3.750" stroke crank with 2.450" mains (350) and it's an internally balanced set up.

I mentioned that all my rods weighed the same so I only had to bring one rod when I had it balanced. The machinist that balanced my assembly only wanted one complete piston/rod set up. Scat weighed all the rods and marked the weight on the box. I forgot what they weighed, I'm going to be doing a little more work on it later. I'll look and see the what the weight on them is.

You're never going to be able to use stock 400 5.565" rods in an internally balanced set up.

also,, when i balance a neutral balance setup like a 350,, i still recommend having the damper and flexplate, because after i get the balance in there without the damper and flexplate,, i mount up the damper and flexplate and match those to the crank. they become one.
it'll be "close enough",, but,, just because it's said they are neutral balanced,, doesn't mean they're spot on every time. i still check and correct at the damper and flexplate with them mounted up if needed. just my way, but it keeps things right after getting the crank right. hope it helps.
andy

I'm with you and I don't trust anybodies parts , I've seen too many "matched assemblies",and supposed neutrally balanced balancers and flex plates that weren't even close to trust any numbers written on a box .
I check everything and have never figured it wasted my time .

Scat weighed all the rods and marked the weight on the box. .

ok :):)

get a balancing scale and check em out.

ok :):)

get a balancing scale and check em out.

Amen to that we've both witnessed that;)

see what jegs gets for this one
http://www.gmpartsdirect.com/performance_parts/store/catalog/Product.jhtmlPRODID=900&CATID=895.html

ok :):)

get a balancing scale and check em out.
They weighed exactly what Scat said they weighed. I've been dealing with two different machine shops. One directly, and one indirectly. The shop that did my machine work and the shop that does all their balance work. They've been doing business together for 20 years. And are both very successful.

I was going to use an Eagle rotating assembly. The guy at the shop that did my machine work recommended I use Scat products instead. He said Scat's stuff was better in over all quality and their machine work was usually better then Eagles. I did what he recommended and everything has checked out to be exactly what Scat said it was going to be. The guy that did the balance work said pretty much the same thing.

The shop that did my machine work checks everything they can check so the other shop can turn their balancing work around quicker. They check rods for length, big end and pin end diameters, side width and weight (I checked bearing clearances .0025" ± .0002"). Pistons for proper compression height, overall OD, pin hole ID, pin OD, piston & pin weight. They check cranks for runout, main and journal OD, journal widths and I'm sure I missed a few things they check. My rods weighed exactly what Scat said they weighed.

To save time so I wouldn't have to wait I took it to the other shop to be balanced myself. They wanted my crank and one complete piston and rod set up. A piston, wrist pin, rod, a set of rod bearings, wrist pin clips, a top, 2nd and the oil rings and ring spacer. He didn't want the balancer or flexplate. That's all I can say.

I've never used Eagle's products so I can't speak about their stuff. However I am very pleased with Scat. For the money I paid the Scat stuff checked out great. The crank mains are 2.449" ± .0002" making my bearing clearances .003" ± .0002". The rod journal OD's are 2.099" ± .0002" making my bearing clearances .0025" ± .0002. Rod side clearances are .010" + .002". None are under .010".

They weighed exactly what Scat said they weighed. I've been dealing with two different machine shops. One directly, and one indirectly. The shop that did my machine work and the shop that does all their balance work. They've been doing business together for 20 years. And are both very successful.

I was going to use an Eagle rotating assembly. The guy at the shop that did my machine work recommended I use Scat products instead. He said Scat's stuff was better in over all quality and their machine work was usually better then Eagles. I did what he recommended and everything has checked out to be exactly what Scat said it was going to be. The guy that did the balance work said pretty much the same thing.

The shop that did my machine work checks everything they can check so the other shop can turn their balancing work around quicker. They check rods for length, big end and pin end diameters, side width and weight (I checked bearing clearances .0025" ± .0002"). Pistons for proper compression height, overall OD, pin hole ID, pin OD, piston & pin weight. They check cranks for runout, main and journal OD, journal widths and I'm sure I missed a few things they check. My rods weighed exactly what Scat said they weighed.

To save time so I wouldn't have to wait I took it to the other shop to be balanced myself. They wanted my crank and one complete piston and rod set up. A piston, wrist pin, rod, a set of rod bearings, wrist pin clips, a top, 2nd and the oil rings and ring spacer. He didn't want the balancer or flexplate. That's all I can say.

I've never used Eagle's products so I can't speak about their stuff. However I am very pleased with Scat. For the money I paid the Scat stuff checked out great. The crank mains are 2.449" ± .0002" making my bearing clearances .003" ± .0002". The rod journal OD's are 2.099" ± .0002" making my bearing clearances .0025" ± .0002. Rod side clearances are .010" + .002". None are under .010".

Did you only check the overall rod weight or did you compare all the big ends and then all the small end weights , that's where you usually find the surprise .

efh, I didn't check the rod weights. I don't have the proper equipment to do it. My main machine shop checked them. They told me they were what Scat said they were. They were all the same as were the pistons and pins too, so the shop that balanced it for me one wanted one complete piston and rod set up. They only had to remove a little material to balance the crank.

efh, I didn't check the rod weights. I don't have the proper equipment to do it. My main machine shop checked them. They told me they were what Scat said they were. They were all the same as were the pistons and pins too, so the shop that balanced it for me one wanted one complete piston and rod set up. They only had to remove a little material to balance the crank.


from what im reading your the luckiest bastard on the planet!!!!! all your pistons wieght the same....all your rods... and all your clerances are perfect out of the box....i wish i had your luck because in the last 8 engines or so i have done, none if this was bang on....next your going to tell us your out of the box rings are perfectly gapped... :) :) :) :) :)

efh, I didn't check the rod weights. I don't have the proper equipment to do it. My main machine shop checked them. They told me they were what Scat said they were. They were all the same as were the pistons and pins too, so the shop that balanced it for me one wanted one complete piston and rod set up. They only had to remove a little material to balance the crank.

Any idea what your guy balances to , 10 grams? ,5 grams?, 3?, 1?, 1/2 gram
If it's 3grams or less then you are the lukiest guy that I've met in years and should have bought a lottery ticket ,because I've never had a kit where all the parts were that close , but then I've seen a lot of balance jobs that I call a okay starting point to begin balancing:) and even on a neutral balance I still make sure that I have the balance and flex plate to verify that they are what they are supposed to be .
You'd think that something that is perfectly round should be easy to make right but you'd be suprised how many aren't in balance .

Any idea what your guy balances to , 10 grams? ,5 grams?, 3?, 1?, 1/2 gram
I honestly have no idea. I won't go back to the shop that did the balance work again until I build my next motor. That won't be anytime soon. His shop is a ways away. That's why I took my parts to him instead of waiting until my machine shop had a few jobs for him to do.

Any idea what your guy balances to , 10 grams? ,5 grams?, 3?, 1?, 1/2 gram


within 1/2 to 1 gram on the parts. and within/less than 3 oz. at 1" from the centerline axis while rotating on the machine is the norm. i'm with ya.
andy

within 1/2 to 1 gram on the parts. and within/less than 3 oz. at 1" from the centerline axis while rotating on the machine is the norm. i'm with ya.
andy

Good to see someone else who knows his way around a rotating assy and had the same type of experiences that I've had with the "it's good to go right out of the box" suppliers
I'm really starting to like you we seem way toooo much alike , if you ever make it up to Ontario , Louch and I will make sure you have a good time

I had a guy bring me a stroker kit for an LS Chev just to check because it had come from one of those for an extra $$we will also balance it for you , turned out the shop that had balance the crank had never seen any of the other parts and had been told over the phone what they were suppose to wiegh ..........THEY DIDN"T:D

next your going to tell us your out of the box rings are perfectly gapped... :) :) :) :) :)
Nope. They had to be gapped. The gap ends on the top and 2nd rings were .012" or so out of the box. I opened the top up to .022" and the 2nd to .016" per Total Seals recommendation. The oil ring rails were right around .025". I didn't touch them.

Tonight I broke a 2nd ring. I gotta call Total Seal tomorrow to see if they'll send me another one. Or to see how to pay for another one. I don't want to buy another complete piston ring set up. All I need is one ring.

But yes, unless my main machine shop did work on my pistons and didn't charge me for (WHICH I HIGHLY DOUBT), even the piston and pin weights were in spec to be balanced. They didn't touch my rods, they were in from Scat. And like I said, only a little material had to be removed from the crank to get it to balance.

I guess them recommending I use Scat products was a good choice. All the other spec's I gave on this thread were right out of the box.

Don't believe me...I couldn't care less! :)

I believe you.

Aftermarket stuff is pretty good these days. Wouldn't expect your experience to be true for everyone, but certainly it's very believable. My recent experience with pistons, for example, is that one piston out of every 3 sets is considerably lighter/heavier than the others (enough that it would throw the balance off by more than you would want in a performance application).

If you're building a race engine, NOTHING is going to be good enough out of the box. But that's race stuff, not stock and not even modest street performance on a budget.

Which brings us full circle back to the answer to your question: you need a neutral balanced dampener. You have a neutral balanced dampener now, so that's what you need to replace it with. Don't give a damn what rods or pistons you have in it- that's already been taken care of at the crank, not the dampener.

Will the balance be perfect after the change? Probably there will be a few grams of difference in the balance, but nothing you will likely ever notice. People change balancers all the time without rebalancing.

You're making this a harder decision than it needs to be (possibly with some help making this sound harder than it really is).

Ask me how many stout and reliable (often daily driven by yours truly) engines I built before I even knew what "balancing an engine" meant. It's important, but being off by a few grams isn't going to make your engine fly to pieces 300 miles after your turn the key the first time.

Stop agonizing. Get a good night's sleep and buy your new dampener tomorrow.

Damon, I'm not the one that asked the original question. owen1980 was the one trying to figure out which balancer to use. My rotating assembly was internally balanced and I have a "in new" condition 8 inch factory harmonic balancer and flexplate. I'm all set.

I kind of laughed earlier when I was looking through my new catalog from Competition Products. Close to 1/2 if not 1/3 of the crate engines and assembled short blocks they sell don't come with balancers and flexplates. Assemblies from GMPP, Dart, Howards, World Products and Tri-Star.

Like I said, I'm all set! :bowtie:

People change balancers all the time without rebalancing.

true,, and even grumpy jenkins has stated that being out 15 grams on one piston/rod assembly they had to replace at the track one day didn't upset anything. bearings showed fine later.
andy

Damon, I'm not the one that asked the original question. owen1980 was the one trying to figure out which balancer to use. My rotating assembly was internally balanced and I have a "in new" condition 8 inch factory harmonic balancer and flexplate. I'm all set.

I kind of laughed earlier when I was looking through my new catalog from Competition Products. Close to 1/2 if not 1/3 of the crate engines and assembled short blocks they sell don't come with balancers and flexplates. Assemblies from GMPP, Dart, Howards, World Products and Tri-Star.

Like I said, I'm all set! :bowtie:

I,m not surprised , bet that they are internally balance motor so they are balanced without balancer and flywheel the way your suppose to balance an internally balance motor , then you verify that the balancer and flywheel are neutral and put them on
Why because I've got a flywheel here right now that was supposed to be neutral and it's out 14.7 grams thats only the equivalent of 15 us 1 dollar bills but the weight multiplies with rpm and also because Scat is using problems with balancer as being one of the reason for their broken crankshaft issues