The Ford Barn

Chris in CT · 11-19-2012, 04:39 PM

OK,OK I was going to try to stay out of this, but I just can't help myself! I'd like you to think about the word, "damping" and throw the balance weight out the window for a moment. That 63 # flywheel was put there to "damp" the impulses from the cylinders as they fired. The 63# flywheel also allowed the driver to "set it and forget it" as far as the timing advance lever was concerned, since at the lower compression of the stock engine the revolving flywheel would easily overcome timing inconsistencies.
What happens with the so-called "counterbalanced" crankshaft is that each of the slings (counterweights) "damps" the combustion impulses right under the subject cylinders, rather than at the end of a long, twisty, spindly piece of forged steel. Once you have effected that "equalization" of combustion impulses, it is no longer necessary to have 63# of cast iron at one end of the engine - in fact, it is counter-productive because it will continue to cause the crankshaft to twist with each impulse where with a lightened flywheel that twist will be proportionately reduced.

The only way to actually prove this to our scientifically-minded brethren is to perform a Fourier Analysis on the rotating assembly, a complicated process requiring a lot of time and equipment.

Oh, incidently, have those of you who have removed 20# or so from your flywheel noticed that the engine is much more sensitive to the position of the ignition advance lever than it was when the flywheel was full weight? I have. So much so that I am tempted to go out and get a centrufigal dizzy! When I go for a drive, it keeps me quite busy trimming the thing. Happy Motoring, Guys!
Chris

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www.burlingtoncrankshaft.com

11-19-2012, 04:39 PM	#11
Chris in CT Senior Member Join Date: May 2010 Location: Connecticut Posts: 272	Re: Is a lightened flywheel overrated? (I think so) OK,OK I was going to try to stay out of this, but I just can't help myself! I'd like you to think about the word, "damping" and throw the balance weight out the window for a moment. That 63 # flywheel was put there to "damp" the impulses from the cylinders as they fired. The 63# flywheel also allowed the driver to "set it and forget it" as far as the timing advance lever was concerned, since at the lower compression of the stock engine the revolving flywheel would easily overcome timing inconsistencies. What happens with the so-called "counterbalanced" crankshaft is that each of the slings (counterweights) "damps" the combustion impulses right under the subject cylinders, rather than at the end of a long, twisty, spindly piece of forged steel. Once you have effected that "equalization" of combustion impulses, it is no longer necessary to have 63# of cast iron at one end of the engine - in fact, it is counter-productive because it will continue to cause the crankshaft to twist with each impulse where with a lightened flywheel that twist will be proportionately reduced. The only way to actually prove this to our scientifically-minded brethren is to perform a Fourier Analysis on the rotating assembly, a complicated process requiring a lot of time and equipment. Oh, incidently, have those of you who have removed 20# or so from your flywheel noticed that the engine is much more sensitive to the position of the ignition advance lever than it was when the flywheel was full weight? I have. So much so that I am tempted to go out and get a centrufigal dizzy! When I go for a drive, it keeps me quite busy trimming the thing. Happy Motoring, Guys! Chris ------------------ www.burlingtoncrankshaft.com