Is a lightened flywheel overrated? (I think so)

[Purdy Swoft]

This time I've got to agree with Vince. I've got model A's both ways and would prefer lighter flywheels in all of them. I run a model B flywheel in my roadster and it out performs the ones with stock heavy model A flywheels. I get faster acceleration, easier gear shifts and less weight has got to be easier on the main bearings. I run other mods like higher compression, two B carbs, warmed up ignition, free flowing exhaust and a Stipe ground cam. My engine is low milage and runs the original Ford balanced rotating assy. It idles good and will chick ah lunk with the spark retarded after a slight warm up. Its got wonderful low end torque. I can let it idle and pop my foot off the clutch pedal and it will take off without choking down. We've never needed to ride the clutch when taking off. I have good hill climbing ability and its got power much like a modern vehicle. This is my experience.

[BRENT in 10-uh-C]

Originally Posted by Purdy Swoft

This time I've got to agree with Vince. I've got model A's both ways and would prefer lighter flywheels in all of them. I run a model B flywheel in my roadster and it out performs the ones with stock heavy model A flywheels. I get faster acceleration, easier gear shifts and less weight has got to be easier on the main bearings. I run other mods like higher compression, two B carbs, warmed up ignition, free flowing exhaust and a Stipe ground cam. My engine is low milage and runs the original Ford balanced rotating assy. It idles good and will chick ah lunk with the spark retarded after a slight warm up. Its got wonderful low end torque. I can let it idle and pop my foot off the clutch pedal and it will take off without choking down. We've never needed to ride the clutch when taking off. I have good hill climbing ability and its got power much like a modern vehicle. This is my experience.

You experience is worth noting and I definitely value it however I cannot help but ponder some folks comments as it relates to actual experience in lieu of what seems believable. Theory has always been a good guide however sometimes it seems misleading. My point with what I highlighted in red is definitely not meant to be critical but instead is to point out something that many others seemingly say too. We all tend to say that it is easier on bearings but I want to know by just how much is it easier on them? I want someone to say with certainty that there is XX percent of additional longevity with the lighter flywheel. Not hypothetical or probability.

Next, exactly how much faster is the engine acceleration with the lighter flywheel? If 0-50mph in a 100% stock engine is 25 seconds, are we saying that it would be more like 23 seconds with the lighter weight flywheel --or 15 seconds with the lighter flywheel? Again, please no assumptions or theories wanted because my unscientific tests shows it to be neglible when both vehicles are driven in the same manner ...much like Mike has suggested above.


One or two other points about Mike's great commentary. If we are truly worried about how many harmonic cycles each component of our Model-A has left, then maybe we should be messin' with different cars or leave them parked in the garage! Even should we choose to run a lighter flywheel to possibly eliminate breakage or failure, at what point do we start worrying about cycle failures of rear axle shafts, or spindles, or steering components?

.

[MikeK]

[QUOTE=BRENT in 10-uh-C;536079]. . . at what point do we start worrying about cycle failures of rear axle shafts, or spindles, or steering components?

We shouldn't beyond reasonable prudence. Life is too short. As we all know, there are two groups of vehicle owners- the users and the possession collectors. I know people with 4x4's that pull the sheets over their head and stay home when it snows an inch or two.

[dave11]

A lightened flywheel does affect the idle condition. A stock model a with a heavy flywheel will idle down to 3 - 400 RPM.
The same engine with a lightened flywheel will idle quite slow but not as smooth.
Important to some folks / not so much to others


Dave

[Ian Crawford]

I can't seehow a lighter flywheel will have any effect on the main bearings. If you take that the flywheel weight is about 63lbs and that on an original engine with a 4.2 c/r the cylinder pressure is about 75PSI. The stock bore is 3.875 so the piston area is 11.80 sq/in which would give us a force of about 884lbs directly on the closest main bearings. That is without the engine even firing. I really don't see that if the flywheel weight is 38lbs or 63lbs would make any noticeable difference. The ballance of the flywheel/clutch assy. will however have a dramatic effect as the out of ballance effect increases by its speed (RPM).