would i get better mileage with the 15# flywheel or the standard 24~#. it is a 71 chevelle sedan daily driver 307 stock.

Just guessing, I'd say the heavier one. The 307 is a little low on torque, and the extra weight would help to move the driveline, and get it going. Where as ,the light weight one would mean you have to rev the engine more, to get the same torque. Light weight flywheels are more of a light car, big gear, highend torque range/H.P thing, to keep the revs up. But someone may have a different opinion. Just my $.02

thanks for the reply. i have always wonder what the effects would be. i just changed my dirt car to the lite flywheel w/lite disc & plate. weighs 19# less than my old assembly. going to try it out tommorrow nite. any predictions. thanks again.

thanks for the reply. i have always wonder what the effects would be. i just changed my dirt car to the lite flywheel w/lite disc & plate. weighs 19# less than my old assembly. going to try it out tommorrow nite. any predictions. thanks again.
it will rev quicker:yes:

The mass of a flywheel will have little or no effect on fuel economy but the heavier one will increase driveability in a heavy vehicle like your '71. At any given RPM the heavier flywheel will have more kinetic energy but, it takes more energy (from the engine) to get it there.

You want a 30lb or heavier one for your application.

thanks for the reply. i have always wonder what the effects would be. i just changed my dirt car to the lite flywheel w/lite disc & plate. weighs 19# less than my old assembly. going to try it out tommorrow nite. any predictions. thanks again.

In addition to accelerating faster, engine braking will be much more pronounced. This might require some different driving techniques.