Please Help with Flywheel Decision

[Dewey29]

Have any of you guys run a stock Model B flywheel (53lb) on a stock Model A crankshaft? I bought a mild touring motor to put in my 29 roadster. The engine came with a lightened flywheel (44lb) and v8 pressure plate, but from what research I've done here, I'm not sure I want to go that light. I'm also installing a 39 tranny with 28 tooth cluster gear for a better shifting ratio.

The stock Model B flywheel seems like a good compromise to improve acceleration without losing too much stored energy for hills? Or it may not make much difference?
I'd really like to hear from someone who has tried the B flywheel on the A crank, did it help performance, create more vibration, or made no difference at all?

I appreciate any help you can give!

[Jim Brierley]

Like any modification, there is controversy here. I am a racer and modifier at heart, also a retired mechanic. I have always run flywheels that are about 30-32 lbs. I have never had any problems with hills. It is your car, do as you like! I am currently running a diaphragm clutch, and it is the best yet!

[BRENT in 10-uh-C]

Originally Posted by Dewey29

Have any of you guys run a stock Model B flywheel (53lb) on a stock Model A crankshaft? I bought a mild touring motor to put in my 29 roadster. The engine came with a lightened flywheel (44lb) and v8 pressure plate, but from what research I've done here, I'm not sure I want to go that light. I'm also installing a 39 tranny with 28 tooth cluster gear for a better shifting ratio.

The stock Model B flywheel seems like a good compromise to improve acceleration without losing too much stored energy for hills? Or it may not make much difference?
I'd really like to hear from someone who has tried the B flywheel on the A crank, did it help performance, create more vibration, or made no difference at all?

I appreciate any help you can give!

The first question I would have is, was the Model-B flywheel balanced to the rest of your engine? If so, how do you plan to rebalance a new flywheel assy. to your present rotating assembly?

FWIW, you will likely find the present flywheel assembly will be fine with the cam that your engine has unless it is a brand new cam. It has been my experiences that if yours is a reground camshaft, they do not produce the same low-end torque as what the IB330 camshaft does. If so, the heavier flywheel is not going to be of much advantage anyway.

[Jim Brierley]

Originally Posted by BRENT in 10-uh-C

The first question I would have is, was the Model-B flywheel balanced to the rest of your engine? If so, how do you plan to rebalance a new flywheel assy. to your present rotating assembly?

FWIW, you will likely find the present flywheel assembly will be fine with the cam that your engine has unless it is a brand new cam. It has been my experiences that if yours is a reground camshaft, they do not produce the same low-end torque as what the IB330 camshaft does. If so, the heavier flywheel is not going to be of much advantage anyway.

4 cyl. engines are not balance as a unit, each piece is balanced separately.

[Terry Burtz, Calif]

Originally Posted by Jim Brierley

4 cyl. engines are not balance as a unit, each piece is balanced separately.

Jim, I agree.

The "New Engine" moving parts (crankshaft, connecting rods, and flywheel) are made in 3 separate factories and each part is balanced when it leaves the factory.

With everything balanced separately, any assembly of random parts will be in balance.

[Dewey29]

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Thanks for your help guys!
I think I made my question more complicated than it is, so allow me to try again.

I'm planning to install the touring motor with a 39 Ford tranny in my 29 roadster. My question or decision I'm struggling with is which flywheel to use? I have 3 options available in my shop at the moment;

1. Use the stock Model A flywheel (65lb) with Model A pressure plate
2. Use the stock Model B flywheel (53lb) with Model A pressure plate
3. Use the lightened Model A flywheel (44lb) with 9" V8 pressure plate

These parts are balanced separately, but not together yet.

I don't know what's the best flywheel option? I live in an area with lots of hills, so is the lightened flywheel (44lb) a disadvantage? Would the B flywheel (53lb) gain any acceleration over the stock A flywheel, without losing too much stored energy for hills?

Thanks Again!!!

[Big hammer]

More information is needed to help you decide, what camshaft, what carburetor, what rear end ratio, what compression heat, what else

[Pete]

Originally Posted by Dewey29

The stock Model B flywheel seems like a good compromise to improve acceleration without losing too much stored energy for hills?

Do you realize that, everything else being equal, you will go up a hill slower with a heavier flywheel?

[johnneilson]

I doubt you would ever know the difference between those two flywheels, unless you ae trying to lug the motor.

FWIW, the total weight of the flywheel is a moot point, what you really need to know is the MOI (moment of inertia)

Most of the information on the web is incorrect about how to lighten the flywheels, it removes the weight but does not maximize the MOI benefit.

Drive it as it is, if you don't like it then make a change, it is like salting your steak before tasting it...

J

[Richard Knight]

Just use the lightened flywheel with V8 pressure plate. You have a light car. The response of the engine to the throttle will make up for any lost inertia. Yes other factors mentioned affect the overall picture. Any good balancer will balance all the parts seperately.

[nkaminar]

Years ago, before lithium-ion batteries, some experimental busses were built using large flywheels that were used for acceleration. There was a complicated gearing system involving the engine. The flywheel was spun up during braking and then used to get the buss going again after the stop. The engineers discovered that a flywheel that was tapered from the hub to the tip could store more energy because the stress in the flywheel was more uniform. The flywheel shape was very much unlike the flywheels used on old hit and miss engines or old steam engines. The flywheel ran in a vacuum.

[BRENT in 10-uh-C]

Originally Posted by Jim Brierley

4 cyl. engines are not balance as a unit, each piece is balanced separately.

Jim, maybe the proper wording should be "4 cyl. engines should not be balanced as a unit, ...instead each piece should be balanced separately."

Originally Posted by Richard Knight

Any good balancer will balance all the parts seperately.

Richard I agree 110% with you in this regard ...however I mentioned that above for two reasons. In my line of work, I have seen it many times where the crankshaft and the flywheel were balanced together as an assembly. I feel certain others have experienced the same.

The second reason for mentioning this is for Dewey to be aware of this possibility. Us/Him assuming something was done correctly (...especially when it apparently was not purchased directly from the rebuilder) is foolish at best IMHO. While duly noted that Mr. Burtz is properly following accepted protocol with balancing his new engine's rotating assemblies separately, it did not appear the original poster had purchased a Burtz engine for his Roadster. Am I missing something??

[62pan]

More info would help but I'll share my thoughts. My fenderless 31 roadster ran a stock A engine that was upgraded with a 6-1 head, B cam and downdraft carb. Flywheel was lightened to 42 pounds with a V8 clutch and a B transmission that was upgraded with the 28 tooth cluster. Rear was a stock 3.78. Living in Pa. we have plenty of hills and I never had any issues with any of them. Sounds to me like your on the right path to a very enjoyable car.