Ballancing a 1973 340

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trigger_andy

trigger_andy

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Hey All,

I have an Aussie Charger that Im currently converting from a 318/904 to a 340 4-Speed. The 4 Speed is a Borg Warner and specific to Australian Mopars.

Im trying to firgure out how to get it all ballenced up and hopefully as cheaply as posible as the work is being done at a garage and they really are not cheap. ($120 an hour!)

My first task is to get the Twin Plate Clutch, intermediate Plate and Fly Wheel all ballanced up. Once this is done then it can be bolted to the 340's crank. But as the 340 is externally ballanced how do I go about re-adjusting the front ballance weight?

Any assistance would be much appreciated. :)
 
trigger_andy said:
Hey All,

I have an Aussie Charger that Im currently converting from a 318/904 to a 340 4-Speed. The 4 Speed is a Borg Warner and specific to Australian Mopars.

Im trying to firgure out how to get it all ballenced up and hopefully as cheaply as posible as the work is being done at a garage and they really are not cheap. ($120 an hour!)

My first task is to get the Twin Plate Clutch, intermediate Plate and Fly Wheel all ballanced up. Once this is done then it can be bolted to the 340's crank. But as the 340 is externally ballanced how do I go about re-adjusting the front ballance weight?

Any assistance would be much appreciated. :)
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G-Day Mate, first you will need to get the proper rotating/reciprocating components for your build. 73 340 is externally balanced so flywheel and crankshaft damper have imbalance. Take the build components to a competent shop that has a good reputation for quality engine building . BTW, good work don't come cheap! Proper balance makes a big difference. 65'
 
You need a 340 externally balanced flywheel, or a drilling template is available. Use a stock damper.
 
Profession products make the balancer with bolt on weights, and McLeod sells a flywheel which also has bolt on weights for the external balance 340.
 
Thanks for the reply. :) The 340 is already installed and I was really hoping it would not need to be pulled again. :( Guess Im not going to get away with that?

Will an Engine Shop be able to ballance the parts I already have or is there no way this can happen and I'd need to buy a new fly wheel and Harmonic Ballancer?

Will the Engine Shop need to have the engine running? There is a very good Shop near me so it should not be such a huge issue.

I thought I was almost there with the conversion but this will really scupper me.

So it looks like I really need to get the 340 back out?

Plymouth 65 said:
G-Day Mate, first you will need to get the proper rotating/reciprocating components for your build. 73 340 is externally balanced so flywheel and crankshaft damper have imbalance. Take the build components to a competent shop that has a good reputation for quality engine building . BTW, good work don't come cheap! Proper balance makes a big difference. 65'
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dogbreath said:
You need a 340 externally balanced flywheel, or a drilling template is available. Use a stock damper.
Click to expand...

Thanks for the reply.

Ive seen this template on-line. I have no idea what to do with it though. :D I'll assume if I take a new external ballance Flywheel to an engine builders they could see what needs done where and do it for me? Then I could use my Stock Damper already installed and mount the Fly Wheel? How do I ensure the ballance/alignment is correct?
 
trigger_andy said:
I thought I was almost there with the conversion but this will really scupper me.

So it looks like I really need to get the 340 back out?
Click to expand...
You have a 2 choices:
1. Just setup the damper and flywheel with the proper external imbalance weights and bolt them on. BUT...BUT...BUT... if you have bored the block and swapped pistons, then a factor called 'bobweight' has changed, and theses standard external imbalances won't be right.
2. To do this per normal balancing procedures, pull the engine, and dissassemble the bottom end. The rods and pistons are balanced against each other per certain procedures, and once that is done, then the bobweight factor is known. That factor is then used with the crank, flywheel, and damper assembled to balance the crank.

Sorry to be the bearer of bad news.
 
nm9stheham said:
You have a 2 choices:
1. Just setup the damper and flywheel with the proper external imbalance weights and bolt them on. BUT...BUT...BUT... if you have bored the block and swapped pistons, then a factor called 'bobweight' has changed, and theses standard external imbalances won't be right.
2. To do this per normal balancing procedures, pull the engine, and dissassemble the bottom end. The rods and pistons are balanced against each other per certain procedures, and once that is done, then the bobweight factor is known. That factor is then used with the crank, flywheel, and damper assembled to balance the crank.

Sorry to be the bearer of bad news.
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Hey, I think I'll initially go with option A. The 340 is completely stock so no issues there. :D What are these external imballance weights you speak of?

The issue for me is the the Fly Wheel I have is suited to the set up I have which is all Australian. The Tooth number for the Starter etc. I dont know if the Fly Wheel is a different dimention to the US one? If I could keep it the way it is then Id be much happier. But the Fly Wheel I have has already been externally ballanced for the Hemi 6 engine used in Australia. Im not sure how Id go about doing a back yard ballance to just see if I could live with it till I get my other 340 correctly built.
 
If the inside of the engine is all original than you should be OK. I assume that is what you mean by 'stock'?

The damper you show from Summit has 2 external weights that can be bolted on with the supplied bolts; you would use the smaller of the 2 weight for the later 340. There should be other dampers that are good for this.

For the flywheel. there is a weight kit for the McLeod flywheel that you show, PN 564111. But if you are using a different and neutrally balanced flywheel, then the procedure should be to find what weight can be added to any neutral balance flywheel or flexplate for the late 340, and place it on your flywheel at the same distance from the crank centerline, and at the same angle relative to the crank bolt pattern. The info to add such a weight to a neutral balance flexplate is out there, but I just don't have it handy. Maybe someone will chime in here with that info.

If your present flywheel is already imbalanced then the sure way to redo it is to first neutrally rebalance it, and then unbalance it with the right weight for the late 340.

And note that adding a weight at a certain distance and angle on a flywheel or flexplate can be achieved just as well by REMOVING the same weight at the same distance from centerline but at the OPPOSITE side of the unit. That is the principle at work with items, like the B&M 10235 flexplate as one example.
 
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nm9stheham said:
If the inside of the engine is all original than you shoudl be OK. I assume that is what you mean by 'stock'?

The damper you show from Summit has 2 external weights that can be bolted on with the supplied bolts; you would use the smaller of the 2 weight for the later 340. There should be other dampers that are good for this.

For the flywheel. there is a weight kit for the McLeod flywheel that you show, PN 564111. But if you are using a different and neutrally balanced flywheel, then the procedure should be to find what weight can be added to any neutral balance flywheel or flexplate for the late 340, and place it on your flywheel at the same distance from the crank centerline, and at the same angle relative to the crank bolt pattern. The info to add such a weight to a neutral balance flexplate is out there, but I just don't have it handy. Maybe someone will chime in here with that info.
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Ah I see, you mean I could buy the new Fly Wheel and Damper and add the weights that come with them? Ok, I guess Im gonna have to do this but I simply dont have the money for that now. I'll fire her up when I get the chance and see what she's like 'as is'. But now I know what parts I need and where to get them. :)
 
trigger_andy said:
Ah I see, you mean I could buy the new Fly Wheel and Damper and add the weights that come with them? Ok, I guess Im gonna have to do this but I simply dont have the money for that now. I'll fire her up when I get the chance and see what she's like 'as is'. But now I know what parts I need and where to get them. :)
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I never use bolt on weights on the flywheel. Don't think I've personally seen them. You can machine the weight from the backside of the FW in an a mill. I used a rotary table.

Me personally, I'd never do what you are asking. I'd make you bring me the cranks and parts so I can weigh them myself and do the job correctly. But that's just me.

I don't step over a donut to pick up a dog turd. In other words...a balance job is not a place to cut a corner. I can't tell you how many I've had to fix but it's in the dozens and it will cost you way more to try and slide by. It's better to be lucky than good. I have no luck.
 
Brewers sells a new 340 externally balanced flywheel for $230 and you should be able to get a stock type balancer for under $100
 
dogbreath said:
Brewers sells a new 340 externally balanced flywheel for $230 and you should be able to get a stock type balancer for under $100
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Hey,

So you reckon Id only need the Brewers Flywheel? Get it balanced for the Cast Crank 340 and get a new stock type balancer? I already have a stock type balancer so would I really only need the fly wheel?
 
yellow rose said:
I never use bolt on weights on the flywheel. Don't think I've personally seen them. You can machine the weight from the backside of the FW in an a mill. I used a rotary table.

Me personally, I'd never do what you are asking. I'd make you bring me the cranks and parts so I can weigh them myself and do the job correctly. But that's just me.

I don't step over a donut to pick up a dog turd. In other words...a balance job is not a place to cut a corner. I can't tell you how many I've had to fix but it's in the dozens and it will cost you way more to try and slide by. It's better to be lucky than good. I have no luck.
Click to expand...

Ok, points taken. Thank you for your input.
 
trigger_andy said:
Ok, points taken. Thank you for your input.
Click to expand...


Just so you know...these things will run without shaking with a considerable amount of imbalance. I've seen both ends off as much as 60 grams and not shake. The reason I mention this is because I've also seen some stuff that was out 30 grams on one end and shake like a dog pooping peach seeds.

I'm the first to admit that there are somethings (a lot really) I don't understand the frequencies involved and what can actually cause a shake. Sometimes it can just be the resonance frequency of the sum of the parts that will tolerate a higher imbalance that another combination may shake with. There is a bunch of science to it.

That's why I'm always leery of trying to balance parts seperate from each other. You can get, let's say the flywheel end to under a gram, and balance the FW, PP and disc to a gram or so and bolt it up and it will change the flywheel end by 10-15 grams. I can't say why, but maybe someone here can explain it.

Just be careful that you don't end up spending money twice.
 
trigger_andy said:
Ah I see, you mean I could buy the new Fly Wheel and Damper and add the weights that come with them? Ok, I guess Im gonna have to do this but I simply dont have the money for that now. I'll fire her up when I get the chance and see what she's like 'as is'. But now I know what parts I need and where to get them. :)
Click to expand...
You didn't "connect all of the dots" in what I said. You can:
1) find out what weight is needed on the flywheel or flexplate for a late 340 and at what angle it gets installed on the flywheel or flexplate (relative to the crank bolt pattern) and at what distance.
2) THEN you REMOVE that amount of weight at that distance at a point 180 degrees away on the flywheel. That will allow you get this to work with your existing flywheel.

Then you have money for a less expensive damper.

IMHO, you have a bad plan. How will you KNOW what amount of vibration is bad and for how long?
 
yellow rose said:
Just so you know...these things will run without shaking with a considerable amount of imbalance. I've seen both ends off as much as 60 grams and not shake. The reason I mention this is because I've also seen some stuff that was out 30 grams on one end and shake like a dog pooping peach seeds.

I'm the first to admit that there are somethings (a lot really) I don't understand the frequencies involved and what can actually cause a shake. Sometimes it can just be the resonance frequency of the sum of the parts that will tolerate a higher imbalance that another combination may shake with. There is a bunch of science to it.

That's why I'm always leery of trying to balance parts seperate from each other. You can get, let's say the flywheel end to under a gram, and balance the FW, PP and disc to a gram or so and bolt it up and it will change the flywheel end by 10-15 grams. I can't say why, but maybe someone here can explain it.

Just be careful that you don't end up spending money twice.
Click to expand...
The "shake" is called rigid body motion. This is due to many factors that includes engine geometry, component stiffness, inertia and cylinder pressure. This rigid body third order has a high amplitude low frequency vibration. The closer you can get your rotating/reciprocating components to zero imbalance the less rigid body vibration. Unbalance is a term used to describe the force of imbalance. Since this motor is together I would recommend the 73 340 stock flywheel and damper. 65'
 
nm9stheham said:
You didn't "connect all of the dots" in what I said. You can:
1) find out what weight is needed on the flywheel or flexplate for a late 340 and at what angle it gets installed on the flywheel or flexplate (relative to the crank bolt pattern) and at what distance.
2) THEN you REMOVE that amount of weight at that distance at a point 180 degrees away on the flywheel. That will allow you get this to work with your existing flywheel.

Then you have money for a less expensive damper.

IMHO, you have a bad plan. How will you KNOW what amount of vibration is bad and for how long?
Click to expand...

Ok, I see what your saying now. :)

The issue is Im using a Flywheel from an Australian Mopar that is externally balanced and has been drilled in three places for balance for a Hemi 6 engine. Would it not be next to impossible to then re-drill it to act as a Cast 340 Flywheel now by just doing what you suggest?

Ive been told by guys in Australia that have used the Hemi 6 flywheel on a Small Block this is the easiest way to go and they have done so without issue. But there is very few 340's in Oz and loads of 318's and a few 360's so maybe they had done the auto to manual conversion using an early 340 or most likley a 318?

I know nothing about any of this process and all this is new to me, hence why Im asking questions and trying to find the best solution and also a solution I can also work with. So I dont KNOW what amount of vibration is bad and what amount of vibration is acceptable. I simply have no idea and so Im asking questions here and in Australia. I assumed if the engine appeared to run smoothly then it would be acceptable. If this is not the case then I need to start looking at buying the required parts.
 
yellow rose said:
Just so you know...these things will run without shaking with a considerable amount of imbalance. I've seen both ends off as much as 60 grams and not shake. The reason I mention this is because I've also seen some stuff that was out 30 grams on one end and shake like a dog pooping peach seeds.

I'm the first to admit that there are somethings (a lot really) I don't understand the frequencies involved and what can actually cause a shake. Sometimes it can just be the resonance frequency of the sum of the parts that will tolerate a higher imbalance that another combination may shake with. There is a bunch of science to it.

That's why I'm always leery of trying to balance parts seperate from each other. You can get, let's say the flywheel end to under a gram, and balance the FW, PP and disc to a gram or so and bolt it up and it will change the flywheel end by 10-15 grams. I can't say why, but maybe someone here can explain it.

Just be careful that you don't end up spending money twice.
Click to expand...

Thanks again. :)

The garage is going to bolt everything up and see how she runs. If it shakes and vibrates then I'll just take it as it is, park her up and wait till I can afford the parts I need to order.

For the 318/904 to 340/4 Speed conversion the Garage has charged me close to $8000 now and Im simply out of funds. The cost has gotten way out of control and I have to put a stop to it now. This included work that was not foreseen, ie the 340 I bought for the project came over from the US last year in a 1976 B200 Van. No one knows how it got there and no one even knew it was a 340. But it had a 2bbl on and a rear mounted Sump. So its now got the correct mid mounted sump and pick-up, a Weiand Action Plus and a 670 Street Avenger. I piad for the parts separately but the work done to get them installed was done at the Garage.
The Oil Filer is also a remote one from factory in Australian A Bodies due to the US engines being off-set for American A Bodies and as there is now even less room for our Right Hand Drive Steering Columns the Oil Filter simply has no where to go, so its plumbed up to the Intake and bolted there. Of course this did not mate up with the Weiand so new plumbing and brackets where needed. Lots and lots of little things like this have put the project well past budgest and now I just want to get it buttoned up and home. Then if there is still issues I can do the work myself.
 
trigger_andy said:
Would it not be next to impossible to then re-drill it to act as a Cast 340 Flywheel now by just doing what you suggest?
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Maybe or maybe not. I can't tell you since I don't know the imbalance that has been put into your flywheel at present, and at what location. Your present imbalance can be takne out by drilling the same hole pattern at the opposite side of the flywheel. And then a new set of holes drilled. Whether it would end up like swiss cheese, I don't at this time know LOL.

And the hemi 6 imbalance could be already very close to the late 340, or could be such that it would make things a lot worse. But it could all be figured out by comparing the imbalance needed for the hemi6 versus the imbalance needed for the late 340's.

If it helps you to work this out, this is all actually straightforward to understand. Imagine you are spinning around (without getting dizzy) and you hold a fixed amount if weight at with your right arm half extended. That imbalance is called a moment and is specified by simply multiplying the weight by the distance from the center of rotation. The more the weight OR distance from center, the more the moment. The moment angle is where it is relative to a reference angle; in the case of you spinning around, the reference angle could be where you are facing. If you changed the weight from the right hand to the left hand, you changed the moment angle by 180 degrees.

The same applies here for your flywheel; a certain weight at a certain distance gives you the right moment. The angle relative to the 6 bolt pattern gives you the right moment angle. Or, you can place 'anti-weight' (drill a hole) at the opposite angle and achieve the same thing.

I would first be finding out the hemi 6 moment and angle and comparing it to the late 340 moment and angle. I can probably dig out the latter info, but I am not so sure on the hemi 6 info. Do you think you could find some info on the hemi 6, like how a neutral balance flywheel is imbalanced for the hemi 6? The info would look like this diagram about 1/3 down in this thread:
A question of balance..............(Mopar related)

If you can find the hemi 6 diagram, I'll find the late 340 diagram and try to find time to compare them.

And if you have photos of both side of your flywheel, that would be good to post.

Of course, if you can't do the drilling yourself, and have to pay, then this might not work with the present financial situation. But it sure would be the least cost way to get the flywheel that you have to what you need.
 
Hello again. :)

Been a busy few days and Ive been switching from 15 days of night-shift to day-shift without a break and Ive been a zombie. :D

As Im working on an Oil Rig away from home Im unable to get a picture of the FlyWheel and I dare not ask the Garage as they are moody buggers. I do have a picture but its of the Pallet of 4 Speed parts I had shipped over from Australia. Everything is cleaned up now though.

Thats a good idea regarding fining out about the Hemi 6 balance, Ill do that, thanks. :)

Paying for the Drilling is not a problem, but if I have to start ordering hundreds of dollars worth of parts then the shipping to the UK and the Tax and Import Duty involved thats not an option just now.
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http://i1250.photobucket.com/albums/hh524/andy_harris4/_20_zpsdrxnvxjs.jpg

nm9stheham said:
Maybe or maybe not. I can't tell you since I don't know the imbalance that has been put into your flywheel at present, and at what location. Your present imbalance can be takne out by drilling the same hole pattern at the opposite side of the flywheel. And then a new set of holes drilled. Whether it would end up like swiss cheese, I don't at this time know LOL.

And the hemi 6 imbalance could be already very close to the late 340, or could be such that it would make things a lot worse. But it could all be figured out by comparing the imbalance needed for the hemi6 versus the imbalance needed for the late 340's.

If it helps you to work this out, this is all actually straightforward to understand. Imagine you are spinning around (without getting dizzy) and you hold a fixed amount if weight at with your right arm half extended. That imbalance is called a moment and is specified by simply multiplying the weight by the distance from the center of rotation. The more the weight OR distance from center, the more the moment. The moment angle is where it is relative to a reference angle; in the case of you spinning around, the reference angle could be where you are facing. If you changed the weight from the right hand to the left hand, you changed the moment angle by 180 degrees.

The same applies here for your flywheel; a certain weight at a certain distance gives you the right moment. The angle relative to the 6 bolt pattern gives you the right moment angle. Or, you can place 'anti-weight' (drill a hole) at the opposite angle and achieve the same thing.

I would first be finding out the hemi 6 moment and angle and comparing it to the late 340 moment and angle. I can probably dig out the latter info, but I am not so sure on the hemi 6 info. Do you think you could find some info on the hemi 6, like how a neutral balance flywheel is imbalanced for the hemi 6? The info would look like this diagram about 1/3 down in this thread:
A question of balance..............(Mopar related)

If you can find the hemi 6 diagram, I'll find the late 340 diagram and try to find time to compare them.

And if you have photos of both side of your flywheel, that would be good to post.

Of course, if you can't do the drilling yourself, and have to pay, then this might not work with the present financial situation. But it sure would be the least cost way to get the flywheel that you have to what you need.
Click to expand...
 
trigger_andy said:
Been a busy few days and Ive been switching from 15 days of night-shift to day-shift without a break and Ive been a zombie. :D

As Im working on an Oil Rig away from home Im unable to get a picture of the FlyWheel and I dare not ask the Garage as they are moody buggers.
Click to expand...
'Moody buggers'... that is funny LOL. And yes, making a living continues unabated. Unfortunately, I could not view the pix.
 
The Australian A Bodies used the 9.5 in flywheel we had in our early A's. I might be mistaken. You will have to count flywheel teeth or measure your clutch/pressure plate. The specs for the external balance on the 73 340 flywheel is known and can be verified and modified by a competent machinist. What does your front damper on the 340 say? Can you post a picture? Do Australian 73 340's have a cast crank? See Yellow Roses post. The next problem will be the Borg Warner 4 speed behind a 340...
 
66fs said:
The Australian A Bodies used the 9.5 in flywheel we had in our early A's. I might be mistaken. You will have to count flywheel teeth or measure your clutch/pressure plate. The specs for the external balance on the 73 340 flywheel is known and can be verified and modified by a competent machinist. What does your front damper on the 340 say? Can you post a picture? Do Australian 73 340's have a cast crank? See Yellow Roses post. The next problem will be the Borg Warner 4 speed behind a 340...
Click to expand...

The Aussie Hemi 6 uses a 148 tooth Fly Wheel. Im now having fun with the Starter Motor. Looks like the 904 in my Aussie Charger has been swapped out in the past as I have an Amerrican 1.3" Pinion on the Starter and not the Aussie 1". There is two in Oz actually, 25mm 9 tooth and a 27mm 10 tooth for the 148 tooth flywheel, just to make things more complicated. :D So before I can even fire up the 340, which was sourced from the US, I need an Aussie Pinion. Fun and games.

Cant post any pictures just now as Im working Off-Shore and the Mechanic is not the best at responding to requests. :D

The 340 has a funny story behind it;

I guy way up North of Scotland mentioned in passing he has a 340 for a Dodge and was thinking of selling it. Took me by surprise and I offered to buy it. The story goes it was in a 1976 B200 Van that was imported into the UK from the US last year. The 340 was pulled for one reason or another without the owner ever realising it was actually a 340, they thought it was a 318. The 340 had been modified to what I can only assue run in the Van with a 2bbl Intake and Carb and a Sump and pick-up to suit the Van. Its now fitted with a Wiand Action Plus and a Holley 670 Street Avanger, and the correct pick-up and Sump. Just need to fire it up once the Starter Motor issue is fixed.

You think there will be an issue running the BW behind a '73 340?
 
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