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to balance or not to balance: 360

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    Posted: Feb/10/2019 at 3:26pm
So I have my Car apart fixing everything that i did wrong when I was young and dumb and put this thing together.  The 360 was a mild rebuild, 10 under on the crank, 30 over cast pistons, factory rods.  Only put about 1500 miles on it, barely even broke in.  I remember when i was helping to pull the engine apart that I pried on the harmonic balancer the wrong way until the outer part moved a good 1/8 inch.

So while i have the engine out I would like to put on a new balancer on it, but that may change how the engine is balanced.  So my question is can I have the engine balanced while it is assembled or does it need to be pulled back apart to do so?

It also has a automatic flexplate from a 304.

Or is balancing not really worth it since i never need to run more than 5K rpm?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2019 at 4:03pm
It has to come apart.
Yes, it is worth it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PROSTOCKTOM Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2019 at 4:07pm
The engine has to be apart to balance the componets. I balance every engine I build regardless of use, however there are millions of engines operaing under 5000 rpms that are never balanced. I think you can always tell when an engine has been balanced because it spins a lot smoother. Your car, your money, but odds are in your favor if you don't balance it.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2019 at 4:33pm
Originally posted by PROSTOCKTOM PROSTOCKTOM wrote:

The engine has to be apart to balance the componets. I balance every engine I build regardless of use, however there are millions of engines operaing under 5000 rpms that are never balanced. I think you can always tell when an engine has been balanced because it spins a lot smoother. Your car, your money, but odds are in your favor if you don't balance it.

Tom
I have one 360 that is balanced, and one that isn't. I can feel the difference in smoothness. The difference probably isn't noticeable unless I drive them back to back.

Edited by Sonic Silver - Feb/10/2019 at 5:21pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2019 at 4:46pm
First question I would have is did the engine run smooth when it was running at all RPM ranges you took/take it to?
If the engine ran smooth, then you really only need to match balance the changed components.
In your case the balancer and flex plate if you are changing it.

I currently have a 401 that I have overbored and am changing pistons, rings, wrist pins and doing new bearings.
It turns out that the new pistons, rings and wrist pins, total each, are only 1.5 g different then what was currently in the motor. A shop (unless a very, very expensive shop) cannot balance a V8 to show that 1.5g difference. It's not being re-balanced.

We use to balance everything at my old workplace, every time we worked on it. Records would show that 10g either way would not show, 15g and you see a spike develop.

Nascar, will overbalance an engine for high RPM running. A diesel truck engine should be under balanced.

I'm not stating that balancing is not important - it is, but, if your talking bolt on components that can be matched to original components, it is not worth the cost of re-balancing everything.
My opinion.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wheelz Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2019 at 6:03pm
rebuild the original damper install and be done with it in this application. Likely not enough difference in piston weightto have a great effect under 5k rpm . The 304 flexplate could be a bigger problem but unsure
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Post Options Post Options   Thanks (1) Thanks(1)   Quote BDCVG Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2019 at 6:09pm
Definately get a rebuild from Damper Doctor or Damper dude and if You can afford the balance it's worth it. Probably contribute to longevity too.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote motorhead_1 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2019 at 6:23pm
the 304 flexplate on the 360 likely already destroyed the thrust bearing. been there. done that. didn't get a tshirt. got a rebuild instead......
what's your crank end play?
is the balancer 360 or 304?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Softbuster Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2019 at 7:02pm
The balancer is original to the 360,  my only concern with rebuilding it is that it comes back exact so that i dont end up with timing (and balance) off.  So a good rebuild place is what i'm looking for.

How would i check end play?  Where is the thrust bearing and how do i check it.
The 360 is on a stand and i can do some things but it will not be coming apart simply to balance the rotating assy.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Softbuster Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2019 at 7:07pm
The torque converter of the trans bolts to the flexplate and is full of fluid, should't the fluid find the imbalance and alleviate some of it?
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