Model B flywheel.

[headonz]

How many lbs can I safely have removed from my counterbalanced B motor flywheel ?

[Dodge]

20-25 easily with no issues

[headonz]

wow really !! I was thinking about 12 lbs hmmm !

[nkaminar]

The flywheel/crankshaft is a dynamic system. Changing the flywheel will change how the crankshaft responds to torsional vibration. The B crank is stiffer than the A crank so the flywheel can be lighter. But I would contend that the Ford engineers knew what they were doing and leaving the weight alone will provide the smoothest running engine, torsional vibration wise.

If you do remove weight you will have faster acceleration but have more torsional vibration. Your choice.

[headonz]

Yes ,these are all factors to consider but I think there has been progress in understanding since 1930 and with the upgrades improvements can be made .How much weight could / should be removed to complement the insert bearings , 6.1 head , 2 barrel down draft webber and extractors to enable me get up the hills and mountains in this part of the world.

[nkaminar]

Sponsored Links (Register now to hide all advertisements)

Reducing the weight of the flywheel will only increase your acceleration, not power. You have done all the right things to increase your power. I can only suggest an improved cam and an over drive. First the over drive. That will help more than the cam. I use second over a lot in the hilly country were I live. With the changes you made you should have double the power but at higher rpm. The higher compression head will help with torque but the Weber will help at the higher rpm.

[Bob Bidonde]

nkaminar has it right. Here is why. Newton's Law that Force = Mass x Acceleration indicates that if the Mass of the flywheel is decreased, then the magnitude of Force to Accelerate is also decreased. So for the same amount of Acceleration, it takes less Force (throttle opening).

[David in San Antonio]

I recently installed a high compression head (6.5:1) with a counterbalanced crank, and a lightened flywheel. The engine pulls harder, of course. It’s not as relaxing, because the engine picks up and loses revs much more rapidly with changes in the throttle. I presume this is a combination of the higher compression making more torque and more compression braking, along with the lower mass flywheel. The engine definitely vibrates a lot more, too. It’s not as sweet, but definitely accelerates more quickly, more easily reaches top speed, and pulls hills in third that used to require downshifting to second or first. I do wonder if it would be appreciably smoother had I stayed with the original flywheel.

[alexiskai]

I hadn’t considered before that reducing the flywheel weight could help with engine braking. Seems like a good thing? Obviously requires adjustment of shifting behavior.

[Richard Knight]

What David in San Antonio may be feeling with "increased vibration" may be the reduced dampening affect of the reduced mass of the of the rotating assembly and the increase of compression ratio. The stock rotating mass of flywheel 62 lbs, pressure plate 18lbs, disc of 7 lbs, and pulley of 2lbs is almost 90lbs. These numbers are from memory. I don't know what weight Dave's lightened flywheel is and did he change to a different pressure plate or not. The stock rotating assembly seems to do a great job of dampening the affects of the combustion cycle. So raising the compression and reducing the dampening may contribute to more vibration generally felt in the steering wheel.

[Jim Brierley]

I cut mine down to about 35 lbs., and would never run a stock, heavy wheel again. Performance is better, and the engine is as smooth as ever.

[nkaminar]

The torsional vibration will diminish with higher rpm, so that may be why Jim (Post #11) thinks his engine is "as smooth as ever." Or it may be that his crankshaft/flywheel dynamics are different somehow.

Here is your physics lesson for today: The crankshaft has torsional vibrations at every rpm. Some rpm's have higher torsional vibration than others because the frequency of the forcing moments are close to a critical frequency. There is a spot in the length of the crankshaft where there is no torsional vibration that is called a node point. With a stock flywheel the node point is at the flywheel and all the torsional twist is further forward. With the lightened flywheel the node point moves forward so that now the flywheel has torsional vibration. This can change with a different crankshaft or a vibration dampener added to the nose of the crankshaft.