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Old 07-04-2019, 01:07 PM   #1
daren007
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Default Balancing

What does balancing a model "A" and or model "B" engine accomplish. I see these services available but after having both a "A and "B" balanced I am thinking it a waste of money. Apparently these engines have inherent design issues balancing are not going to correct. Give me your feed back on before and after balancing.
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Old 07-04-2019, 04:03 PM   #2
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Default Re: Balancing

The degree of balance in any rotating part is directly proportional to the rigidity of the mounting.
A 4 cylinder engine with a single plane crank cannot be be so called "completely balanced".
It has the same problem as a single cylinder engine.
You can only balance it for a narrow rpm range.
This is why you still feel a model A engine shake at certain rpm ranges even after being balanced.
You can change the rpm it shakes at but you can't eliminate the shake without engine
re-design.
Certain types of industrial and racing 4 cylinder engines have achieved something close to ideal balance
by using "balance" shafts. This is a counterweighted shaft that is mounted on the oposite side of the
engine from the camshaft with the weights synchronized to counteract the vibration of the crank.

In a model A/B engine, the ideal situation would be to have the harmomic damper the same weight as the
clutch/flywheel assembly to reduce harmonic vibration. This however will not eliminate the felt vibration.
It will prolong the life of the engine though. In the real world this is difficult to achieve but can be
approached by using a damper from a big block Chev.

Reducing flywheel weight has an added advantage in making shifting easier and faster.
All of this modification will all but eliminate TORSIONAL vibration but will not eliminate total engine vibration.
You do not normally feel torsional vibration in the seat of your pants.
Crankshaft counterweights help reduce overall vibration by adding rotating mass and hence damping of felt vibration.
There is not enough room in the "A" crankcase to add enough counterweight to achieve a comfortable "seat of the pants"
vibration level. 60% is about all the weight that can be squeezed in without redesigning the whole engine.

A couple of definitions are offered here for a better understanding about balancing.
Static balancing is balancing in a single plane.
Dynamic balancing means the object is balanced over it's whole length.
Both are done while the part is rotating in the balancer.
Bob weights are not used to balance single plane cranks except for extreme rpm racing engines.
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Old 07-04-2019, 10:14 PM   #3
daren007
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Default Re: Balancing

I see advertised by rebuilders they have a balancing service. This is misleading in my opinion. They should tell you what to expect and what not to expect before spending your money. I would like to hear from others what they experienced after balancing and if they thought it was worth the effort and money.
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Old 07-04-2019, 10:31 PM   #4
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Default Re: Balancing

Quote:
Originally Posted by daren007 View Post
I see advertised by rebuilders they have a balancing service. This is misleading in my opinion. They should tell you what to expect and what not to expect before spending your money. I would like to hear from others what they experienced after balancing and if they thought it was worth the effort and money.
Others will chime in but I will tell you advertising a balancing service is not misleading in any way. There are people on here that advertise head service, cam grinding service, block cleaning and ignition service and many others.

It is up to YOU to determine whether you need any of these services or go to them and have them educate you about their services.

By the way, there is not one QUALITY shop in the country that will turn out a WARRANTEED engine rebuild without balancing.
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Old 07-05-2019, 08:14 AM   #5
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Default Re: Balancing

I have a ‘31 engine with counterweights and a lightened flywheel. The entire rotating assembly has been balanced and it produces 60 HP at the rear wheels at 3500 RPM. I would never build/rebuild an A/B engine without balancing. As to misleading advertising: not.
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Old 07-05-2019, 08:29 AM   #6
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Default Re: Balancing

I can see balancing when you are upgrading but as for a stock engine do you feel it was money well spent. My point in advertising if many think they are getting a smoother running engine seat of the pants feel) are they getting that.
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Old 07-05-2019, 09:01 AM   #7
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Default Re: Balancing

What Pete says! For me it doesn't need explanation, it's intuition. Balanced rotating masses need to weigh the same on all sides. This prevents the centers of shafts (whipping) from moving off axis. This may not sound like much until the bearings that support the shaft begin to wear excessively. Then it all comes together!
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Old 07-05-2019, 09:38 AM   #8
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Default Re: Balancing

Quote:
Originally Posted by daren007 View Post
I can see balancing when you are upgrading but as for a stock engine do you feel it was money well spent. My point in advertising if many think they are getting a smoother running engine seat of the pants feel) are they getting that.
Daren, as an engine rebuilder I balance every engine that comes out of my shop. When the Model-A was being manufactured, Ford balanced every engine that came out of his factory too, ...and Ford would not have taken the time or the added expense if he did not know this was necessary. There are many components we use today during the rebuild which are not in balance with each other (-such as pistons, pins, rods) plus most of the rotating assembly has been modified in some way over the coarse of its lifetime where they are no longer in balance. That is why I choose to balance every component on my engine rebuilds.

Now the underlying issue is that you don't have any way of knowing is how poor the balance 'could be' since your rebuilder DID balance everything. If you are complaining now, it vey well could have been much worse had they not balanced everything.

So you may ask, the why don't all engine rebuilders balance their engines? Maybe it is a marketing ploy where their advertised price can be a couple hundred dollars cheaper than their competitors by making the balancing an option. Maybe it was because the consumer was looking for ways to save a buck. I will offer this mindset though, thee is more time involved to properly rebuild a Model-A engine compared to other more modern marques and yet the profit on a Model-A engine rebuild is less than most other engine rebuilds. What I have personally observed is the way many Model-A engine builders can do them cheaply is because they are using old worn equipment. With worn equipment, the results generally are sloppy tolerances. To some consumers, this is acceptable either because they don't know any better or they just don't care, however to some consumers who live in today's world, they have 21st century expectations when it comes to their Model-A too. Restoring a Model-A engine that can surpass 50k miles of life expectancy is not hard to do if top-notch equipment and skills are used, however it does come with a price that some are unwilling to pay.
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Old 07-05-2019, 10:20 AM   #9
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Default Re: Balancing

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Originally Posted by Terry, NJ View Post
What Pete says! For me it doesn't need explanation, it's intuition. Balanced rotating masses need to weigh the same on all sides. This prevents the centers of shafts (whipping) from moving off axis. This may not sound like much until the bearings that support the shaft begin to wear excessively. Then it all comes together!
Terry
OR it all comes apart.
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Old 07-05-2019, 10:38 AM   #10
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Default Re: Balancing

Balancing will increase the longevity of the engine, and might make it a little smoother. A and B engines have certain RPM's when torsional vibration occurs, this is not usually felt, and balancing will not cure that, but nothing to worry about.
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Old 07-05-2019, 02:23 PM   #11
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Default Re: Balancing

This has always been a confusing issue to me because to my mind shouldn't the rebuilder or the machine shop make sure that all rotating masses in the engine are balanced and if not take the appropriate measures to balance them? I can't imagine why anyone would skip that step, seems like an important one to me. Just like matching pistons, pins, rods, etc.



Then again, I've had plenty of conversations with people at car shows that claim the engines were never balanced from the factory because the stock crank lacks counter weights. I just smile and nod now.
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Old 07-05-2019, 04:34 PM   #12
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Default Re: Balancing

I was surprised after I bought an inserted, balanced, running engine that it wasn't as smooth as my 4 cylinder dodge, now I know why. It does have it's sweet spot. This is my first A, so I had nothing to compare it to, then I drove a friend's A, it drove similar to mine. Good information, Thanks.
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Old 07-05-2019, 04:40 PM   #13
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Default Re: Balancing

Quote:
Originally Posted by ryanheacox View Post
This has always been a confusing issue to me because to my mind shouldn't the rebuilder or the machine shop make sure that all rotating masses in the engine are balanced and if not take the appropriate measures to balance them? I can't imagine why anyone would skip that step, seems like an important one to me. Just like matching pistons, pins, rods, etc.



Then again, I've had plenty of conversations with people at car shows that claim the engines were never balanced from the factory because the stock crank lacks counter weights. I just smile and nod now.

Again, this is likely one of those things where Grandpa made an assumption about how things were done and that information has been passed down as gospel. I have spent many, many hours at the archives reading and collecting factory prints of engine components (-amongst other items.) and I can tell you what it says on most of the prints regarding matching or in the case of the crankshaft, it states the crankshaft must be balanced dynamically within .3 ounce inch at any point of reference. Connecting rods were specified to be 198 grams plus or minus 1 gram, and pistons were to be within 4 grams when finished machined. Even those were matched as a set within those four grams.






With regard to should the rebuilder or the machine shop make sure everything is balanced? Well, again this is one of those things that consumers typically get what they pay for. I have some people tell me I am more expensive than some of my competitors, ...and they are likely correct however there are steps I do that are considered standard by me that are optional by other shops. Even Ford's Model-A was advertised as cheaper than a Chevrolet, -and it was until the bumpers and the engine oil were added into the sale of the Model-A.
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Old 07-07-2019, 10:41 AM   #14
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Default Re: Balancing

Interesting thread, I learned a lot about Ford's balancing process. Now if only someone could help us older folk to keep from falling over.
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Old 07-07-2019, 11:29 AM   #15
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Default Re: Balancing

I would like to build a BB Chevy damper for my 29, I've been to the HAMB, looked at the drawing, I can build it, problem is, I think you have to cut out the bottom of the cross member and you cant use a stock motor mount, if anyone knows another way, please post.
thanks
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Old 07-07-2019, 01:10 PM   #16
Pete
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Default Re: Balancing

Quote:
Originally Posted by nick c View Post
I would like to build a BB Chevy damper for my 29, I've been to the HAMB, looked at the drawing, I can build it, problem is, I think you have to cut out the bottom of the cross member and you cant use a stock motor mount, if anyone knows another way, please post.
thanks
I am not sure about the stock motor mount on a 29, but I used one on my 30 for awhile.
Yes, you do have to trim the cross member back about 1/2 inch.
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Old 07-07-2019, 01:37 PM   #17
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Default Re: Balancing

Quote:
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I would like to build a BB Chevy damper for my 29, I've been to the HAMB, looked at the drawing...
thanks
Nick, do you have a link to this on the HAMB? I would be interested in seeing this. I'm sure others are curious also. Thanx.
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Old 07-08-2019, 09:50 AM   #18
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Default Re: Balancing

https://www.jalopyjournal.com/forum/....781649/page-5
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Old 07-08-2019, 11:47 AM   #19
The Master Cylinder
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Default Re: Balancing

Nick, here is a recent discussion on dampers you may be interested in. No crossmember trimming as it is the same diameter as stock pulley. https://www.fordbarn.com/forum/showt...bration+damper
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