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Chris in CT · 01-31-2014, 10:05 AM

Hi Calvin, Two reasons for the 62 lb flywheel (stock) are: 1. The extra weight serves as an impulse dampener for the non-counterweighted crankshaft; 2. the extra weight allows "set it and forget it" ignition timing in the lower compression antique engine.

When to lighten the flywheel? 1. When the engine has a counter-slung (balanced) crankshaft where impulse dampening occurs directly under each cylinder; 2. When the compression ratio is raised significantly.

Please note unintended consequences of 2. above: If you raise the compression ratio and lower flywheel weight, you will need to play with ignition timing while you are driving, or add a centrifugal-type timing control to your distributor. Some of the guys have complained that they lose power on the hills with the lightened flywheel, but I have found that is not at all the case. But I do have to fiddle with the spark lever until I find the "sweet spot" for climbing a hill with my own '29 roadster (counter-slung crank, 5.5 head, and 40 lb flywheel).

I'm sure that some of the other guys will have something to add to this...

Happy Motoring! Chris

01-31-2014, 10:05 AM	#2
Chris in CT Senior Member Join Date: May 2010 Location: Connecticut Posts: 272	Re: lightened flywheel Hi Calvin, Two reasons for the 62 lb flywheel (stock) are: 1. The extra weight serves as an impulse dampener for the non-counterweighted crankshaft; 2. the extra weight allows "set it and forget it" ignition timing in the lower compression antique engine. When to lighten the flywheel? 1. When the engine has a counter-slung (balanced) crankshaft where impulse dampening occurs directly under each cylinder; 2. When the compression ratio is raised significantly. Please note unintended consequences of 2. above: If you raise the compression ratio and lower flywheel weight, you will need to play with ignition timing while you are driving, or add a centrifugal-type timing control to your distributor. Some of the guys have complained that they lose power on the hills with the lightened flywheel, but I have found that is not at all the case. But I do have to fiddle with the spark lever until I find the "sweet spot" for climbing a hill with my own '29 roadster (counter-slung crank, 5.5 head, and 40 lb flywheel). I'm sure that some of the other guys will have something to add to this... Happy Motoring! Chris