[Kenth]

Originally Posted by MPKind

You do understand that the original external balanced Eagle crank was removed and rebalanced to full internal balancing to accept a new neutral balance flywheel, right? Maybe you're responding to a different comment.

Yes i was responding to "Normally you can even swap the ext and neutral flywheels out for each other and they won’t vibrate." in posting #2.

I guess JAY S ment you can swap an ext flywheel with another ext flywheel and a neutral flywheel with another neutral flywheel. (I hope...) :-)

[Jay S]

Originally Posted by Kenth

Yes i was responding to "Normally you can even swap the ext and neutral flywheels out for each other and they won’t vibrate." in posting #2.

I guess JAY S ment you can swap an ext flywheel with another ext flywheel and a neutral flywheel with another neutral flywheel. (I hope...) :-)

Yes that is how it is suppose to work.

[MPKind]

Originally Posted by HWYSTR455

Going to a 68-up balancer setup is the hot ticket, if you're not trying to be stock appearing, that's a great upgrade.

I think I remember comments about the fan clutch. Did you do the water pump at same time? A bad fan clutch can take out the pump bearing. Just a thought there, not related to the vibration (since you tried w no acc), just figured I'd mention it.

Glad the clutch swap was successful too...


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I think the fan clutch bushing was only missing for a short while with minimal time on the parts...maybe an hour or less at normal driving. I got to swapping it out rightaway after the engine was done. Drove it all summer and no water pump issues.


I've been keeping the engine mostly stock appearing and was looking at what's available now. PRW makes an SFI18.1 for 67 and older that would bolt on with no other mods from what I can tell. ATI dampeners are really nice but would likely require other parts swapping (timing cover and water pump) and pulley alignment shimming. That's what I know so far.

[HWYSTR455]

So what's the factory external balance weight? Anyone know that? Guessing it's in the 5-10oz range? Some other brand engines I have heard 50oz thrown around, but that's from memory only.

Because of that, you never know how far out a balancer or flexplate/flywheel is, not only by tolerance, but potential box-swap situations.

The one balance shop I used to use suggested it at one time, and I've always included the balancer & flexplate/flywheel. They didn't charge extra for it so it was no big deal. That's all they did was balancing, pretty sure it was called Crankshaft Specialties, don't think it exists anymore tho...

If there's an SFi balancer made for the earlier engines, I would think it would be a good idea to use it over one that's not, even on a lower performance build, it would aid longevity I believe.


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[MPKind]

My understanding is that the factory dampeners were neutral balanced and the low mass external balance that Pontiac used was only applied to the flywheel/flex plate.

Now the guy that worked the rotating mass did check the stock 2-piece Butler dampener and removed a very small amount of mass to make neutral. Do I know how he arrived at that? No. I would like to think that he neutral balanced each of the 3 major parts (dampener, crankshaft, and flywheel) independent of each other, then assemble to check the entire rotating mass, if that's really needed.

PRW makes a neutral balance SFI 18.1 dampener in their Pro Series that is 5.50" to fit the 59-67 timing cover and pulley offset. Eliminates swapping out other parts, which is preferred. ATI does not make the smaller diameter dampener, but they look like a sweet part.

https://www.prwpower.com/prw-pontiac...-2442101/p3104

[HWYSTR455]

Oh wow that does look nice! And it does state that it's neutral balance.

I honestly am not very familiar with pre-68 balancer setups, or if they were neutral balance from the factory.

The fact that the pulley is part of it makes me question the pulley though. Not sure if someone balancing the balancer/rotating assembly would include the pulley.

How does the pulley look, beat up, or holes wobbed out? Can you post a pic of the balancer? And maybe just the pulley?



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[HWYSTR455]

Just read the instructions for that PRW balancer, and this is the comment for the Pontiac one:

"Pontiac V8 Engines - All 1961 - ‘79 engines - 326, 350, 389, 400, 421, 428, 455
Note that for this damper to fit ‘61 to ‘68 engines, you must use a ‘69 or later model timing
chain cover, water pump, pulleys, and related components. These parts can be sourced
from a wrecking yard or from Year One (800-932-7663, www.yearone.com). Kauffman Racing
Equipment (www.MR-1.com) offers a high-quality ‘69 and later front aluminum timing cover
at a reasonable price, and a similar cover is available from Performance Years (performanceyears.com). These dampers, unlike some competitors, retain the original Pontiac accessory
pulley bolt pattern, allowing you to use your original stock pulleys if desired. The Pontiac
damper is a neutral balance model, essentially the same as those used on all various-sized
Pontiac engines from 1961 through 1979. Additionally, this damper includes a big block
Chevy accessory pulley bolt pattern. Some modifications to the pulley or damper hub may be
required to use BB Chevy pulleys."

Not sure what the benefit would be of going to that, you have to swap the cover, so you might as well go to a '68-up one, it's a one piece. Unless it has something to do with the crank snout?



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[MPKind]

Thanks for pointing that out. The PDF appears to address all applications in the "Pro Series" which makes me skeptical about what's generally written about the Pontiac offerings. The '59-'67 factory dampers are 5.50" diameter. One of the PRW Pro Series dampers is also 5.50" and the other is 6.90". The 5.50" damper appears to have been made to specifically fit the early style cover with the timing marker closer to the crank. Why offer one in that size at all? Doesn't make any sense if it doesn't work with the older style cover. The 6.90" would fit '68 and newer style cover as the tech memo states.

I will call the tech help line and confirm.

[MPKind]

I talked to the tech help at PRW and confirmed that the 5.50" dampener is specifically made for the early style timing cover. So if you want to upgrade, that's the ticket. A new pulley is included, however, this part does not have any degree markings on it, just the single line for TDC...BOOO! Alright so this is an good part for near stock applications. The larger 6.90" dampener would require the newer ('68 and up) timing cover and water pump, and it comes with the degree markings.

I don't know about pulley offsets differences between the 67 and older vs. 68 and newer, so that requires some research if a guy were to go that route. Maybe someone here can confirm.

[MPKind]

Balancing of the rotating assembly shouldn't be that complicated. I've always thought that the more parts attached to the crank, the better the final result. For an internal balanced setup, if the crank is zero balanced by itself then you add a zero balance flywheel and a zero balance dampener, there will be no change in the result, just more mass rotating. When the guy last balanced it for this second go around, he included the flywheel and dampener (2-piece). He took a little mass out of the dampener hub. I don't think you should do that if it's already a zero balanced dampener. 0+0+0=0. Kind of pointless if you consider interchanging dampeners or flywheels. The crank by itself (with bob wts etc) is all that needs to be done. Of course if it's an external balance setup you do need all the attached parts, but that's not what I'm writing about.

So it's possible that Butler 2-piece is no longer zero balanced and could also be inadequate for the 455, therefore causing a narrow band torsional vibration.

Going to swap to a one piece damper. ATI 917160/161 @ ~$400 or Fluidamper 650401 @ ~$600. A '68 edelbrock timing cover and matching crank pulley for the 1-piece damper will complete the upgrade with no changes to the '65 bracket set. ATI damper requires drilling the pulley for 3-bolt. Not a big deal if that's what I choose.

I've provided a little interchange chart that demonstrates the parts you need to upgrade to a 1-piece.

[JLMounce]

Originally Posted by MPKind

Balancing of the rotating assembly shouldn't be that complicated. I've always thought that the more parts attached to the crank, the better the final result. For an internal balanced setup, if the crank is zero balanced by itself then you add a zero balance flywheel and a zero balance dampener, there will be no change in the result, just more mass rotating. When the guy last balanced it for this second go around, he included the flywheel and dampener (2-piece). He took a little mass out of the dampener hub. I don't think you should do that if it's already a zero balanced dampener. 0+0+0=0. Kind of pointless if you consider interchanging dampeners or flywheels. The crank by itself (with bob wts etc) is all that needs to be done. Of course if it's an external balance setup you do need all the attached parts, but that's not what I'm writing about.

So it's possible that Butler 2-piece is no longer zero balanced and could also be inadequate for the 455, therefore causing a narrow band torsional vibration.

Going to swap to a one piece damper. ATI 917160/161 @ ~$400 or Fluidamper 650401 @ ~$600. A '68 edelbrock timing cover and matching crank pulley for the 1-piece damper will complete the upgrade with no changes to the '65 bracket set. ATI damper requires drilling the pulley for 3-bolt. Not a big deal if that's what I choose.

I've provided a little interchange chart that demonstrates the parts you need to upgrade to a 1-piece.

You can consider a BHJ pulley, which is drilled for the factory 4 bolt pulley pattern. Nitemare Performance sells a version that they mill for the AC pulley if you are running that.

http://www.nitemareperformance.com/bhjbalancers.html