Balancing an engine at home (Newbie)

[Straw530]

I have a 30 Tudor that I just got back together. It's my first Model A. I am working to get the bugs out, including a pretty good oil leak. The engine was rebuilt before I got the car. It runs very well, and can go down the road well at 50 MPH, with more to spare. The only problem is the vibration. While I would not call it severe, it is constant. At some ranges it pretty minor, 30 and 50 MPH. Many people tell me it is normal for a Model A, but I would like to make one better. I do have another engine, and would like to rebuild one myself and try to balance the parts myself. I mean the ones I can. Is there some info where I can get ideas on how to do this? I was thinking of buying a balanced crank, and then try to balance pistons, rods etc. Whatever I would need to send out I would, such as bearings. Any help would be great! Thanks

[chrs1961815]

If it is coming from the engine it can be a combination of balancing issues and perhaps the motor mounts depending on what you have.

Now before I go any further, are you positive the vibration is coming from the motor and not something else?

[Synchro909]

Vibration is built into a 4 cylinder motor - it's inherent in the design. Are you sure you are not expecting more than is possible?

[Flathead]

Model A engines will vibrate to some degree no matter how well balanced they are. A poorly balanced engine will vibrate even more.

[Straw530]

I assume it is the engine, because it will vibrate when I idle and rev the engine. I have float a motor mounts on the rear. I had assumed it was the flywheel before I took the car apart, so I took it to a pretty notable Model A guy up here and he said the flyweel was fine, and replaced the crank pulley and distributor rod. (If that is the correct term)

[Mike V. Florida]

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This is just my opinion, that's a lot of money to spend for a little vibration, but your plan sounds good. Don't forget the flywheel and clutch that can cause vibration as well.

[Straw530]

I have been told by other guys that I may be expecting too much from it, but it seems excessive to me. I am hoping to ride in another one so I can compare as well.

[Railcarmover]

I went down to the local 'emporium' and bought a gram scale..balanced the rod piston pin and rings as assemblies,I know it isn't the proper way to balance but I did get them within a gram.they did have a 10g or so variance so it helped.The biggest bang for your buck balancing is getting your flywheel,pressure plate and clutch done as an assembly.

In line four cylinders have an inherent shudder,accentuated in the A with siamese intake ports ,mine runs pretty smooth,thouigh I dont know if the fooling I did with the scale was the difference..probably not

[History]

The first time I took a ride in a model a was last year. A man I know stopped by my shop in his A and said "get in". I hopped in and we took off down the road. I was checking everything out inside and was hit with what I thought was a huge vibration. I asked him why it vibrated so bad and he pushed the clutch in and it quietened waaaayyyyy down. He said they all did it, atleast all of his as he has several.

Starting mine for the first time this past Saturday I can see that it too vibrates.

[old31]

Originally Posted by Railcarmover

I went down to the local 'emporium' and bought a gram scale..balanced the rod piston pin and rings as assemblies,I know it isn't the proper way to balance but I did get them within a gram.they did have a 10g or so variance so it helped.The biggest bang for your buck balancing is getting your flywheel,pressure plate and clutch done as an assembly.

In line four cylinders have an inherent shudder,accentuated in the A with siamese intake ports ,mine runs pretty smooth,thouigh I dont know if the fooling I did with the scale was the difference..probably not

Rail, what did you to balance everything. Grind, file, drill?

[Railcarmover]

Originally Posted by old31

Rail, what did you to balance everything. Grind, file, drill?

I smoothed the casting ridge on the side of the rod. It wast a scientific job,weight variance an the piston has a greater effect on vibration than a weight variance at the big end of the rod,its further from the axis (center of crankshaft)
I figured anything would help,the imbalance on a low rpm engine isnt that big of an issue,as rpm rises (like 4 or 5k) it becomes huge. If memory serves I pulled out a 10g variance.

[ryanheacox]

A good indicator of balance is how fast your car will go, a stock engine should push the car to 65 if all else is good. Any imbalance in the engine will make the engine fight itself.



I thought my car had some bad vibration but it turns out the upper drivers door hinge pin is loose and the horn rod rattles. If I grab the hinge and turn the lights on it seems like a completely different car. I also rubber mounted the tail pipe and that made a noticeable difference.



Moral of the story, you may be able to make driving the car WAY more tolerable without touching the engine.

[BRENT in 10-uh-C]

Originally Posted by Straw530

I have a 30 Tudor that I just got back together. It's my first Model A. I am working to get the bugs out, including a pretty good oil leak. The engine was rebuilt before I got the car. It runs very well, and can go down the road well at 50 MPH, with more to spare. The only problem is the vibration. While I would not call it severe, it is constant. At some ranges it pretty minor, 30 and 50 MPH. Many people tell me it is normal for a Model A, but I would like to make one better. I do have another engine, and would like to rebuild one myself and try to balance the parts myself. I mean the ones I can. Is there some info where I can get ideas on how to do this? I was thinking of buying a balanced crank, and then try to balance pistons, rods etc. Whatever I would need to send out I would, such as bearings. Any help would be great! Thanks

Again, knowing where you are located would help us point you to someone knowledgeable. There are rebuilders out there that do not have balancing equipment, so they assume many things including new parts will be balanced. They produce engines like you are mentioning, ...and my theory is generally if they take a few shortcuts on items like balancing, what else did they take a shortcut on? You did not mention where the oil leak is, and you did not mention how many miles are on the rebuild, but you may be trying to put lipstick on a sow if the thrust is killed or the babbitt is loose which would be causing the leakage.

[kenparker]

I have done exactly waht you are asking about , in my "home shop". It can be done and it does make a difference in the smoothness of the engine. Four cylinder engine VIBRATE, but you can take most of the vibration out.


Balancing an engine and installing a counterbalanced crankshaft are two different things. You should take your new (or old) crankshaft, Flywheel, Cllutch pressure plate, Clutch disc to a professionall balancer. My balancer even wanted the front pulley. Each piece is balanced while rotating, then balanced as a unti. This is to one step most "home shops" do not have the very expensive ewuipment to do.


The balancing of the pistons and rods you can do. Slow and tedious but very satisfiying when you get er done. I had one set of pistons theaat were 20 grams out of balance - out of the box from on e of the majr vendors. Sent them back and the second set was within 4 grams of each other. 4 grams is common acceptance, but not gud nuff for me. I balanced to within 1 gram - pistons with rings. Rods are a little more complicated to balance, but doable. Worth the try.


When I went ot my balancer with the crankshaft, he wanted to see the rods and pistons, then rebalanced them to within 1/4 gram on his homeade equipment. He balances engines for racing engines.

[1930artdeco]

My question is this: How did that guy know the flywheel was good with the engine in the car? One would have to take it out to balance it separately and then with the clutch from what I have seen.


Mine has a bigger vibration at 48/49 mph. Why I am not sure but it is at that exact speed so I know how fast I am going if I feel that.


Mike

[Joe K]

Balancing an engine and installing a counterbalanced crankshaft are two different things. You should take your new (or old) crankshaft, Flywheel, Cllutch pressure plate, Clutch disc to a professionall balancer. My balancer even wanted the front pulley. Each piece is balanced while rotating, then balanced as a unti. This is to one step most "home shops" do not have the very expensive ewuipment to do.

Plus 1. This is where I went with my Model A engine rebuild. And he did take the front pulley - and cut a surprisingly large number of "drill imprints" out of both sides at one location on the rim to make it balanced.

That was a repop pulley, but one would think the issue would have come up with the manufacturers long before and he would have made more effort.

Joe K

[Jim Brierley]

First remove the fan belt to see if that helps. The best way to balance the pistons and rods is with a balance-beam scale but the Post Office sells a good digital scale that reads in ounces and/or grams. 1 gram is the weight of a dollar bill, not much but try and get everything that close. Balance both ends of the rods separately, and total weight. Pistons without rings, pins can be used to make a little difference in piston weight by switching them around. If inserts, don't include them, rings and insert bearings will likely be replaced at one time or another, and weight difference is so little it won't make any difference. Crank, flywheel, etc. should be done professionally. Good luck and have fun

[rotorwrench]

The standard model A crank doesn't have a lot of places to remove weight. The "B" crank or a modified A crank with added counterweights will have a bit more to work with. The clutch and flywheel can be balanced separately but should be indexed to the crank after initial installation checks are completed. Runnout and end play should be checked on everything. Equalizing weight on the pistons and rods is a blueprint tactic and a person doing the balancing on a machine can calculate the bob weight mass from those figures.

The model A or B engine doesn't have a lot of mass in it's rotating assembly when compared to a V8 so they generally can work from their original balance at Ford. It's when parts start getting mixed & matched or modified that there can be problems.

Aligning the clutch housing with the crankshaft flange is another thing that is sometimes taken for granted. If the transmission isn't aligned with the engine, it's going to have problems. When things are right, the model A engine is pretty smooth.

[wensum]

First fit a harmonic balancer pulley, You will be surprised at the transformation and it could save you a great deal of trouble and expense!

[john in illinois]

You said that you have rear float a motors. I found that if you tighten them too tight it will increase vibration. Try loosening or tightening and see. I like to be able to turn the top washer with my fingers.

John