Thoughts on lightened flywheels and clutch disks, For performance motor Options

[Boomingbeetle]

I have a 2270 motor that I will eventually be putting into my '71 with a sideshift tranny, once I get some dress-up and parts collected. It does not currently have a flywheel, clutch, or pressure plate.

1. Is there a benefit to finding a lightened flywheel if the motor has lighter internals?

2. I assume I should use a 6-spring clutch disk or an aftermarket performance material, but maybe this isn't necessary for a 150-HP/TQ motor? Ditto for the pressure plate.

[Mark Henry]

Once you are in 3rd,4th,5th gear a light flywheel doesn't make a hill of beans, this is where gearing changes will make the huge differences.

A lot of the mindset for a lightened flywheel is born from racing, drag racing in particular, but also road racing as well.
It also comes from the VW type 1 world where lightening a flywheel you are going from 18lbs to 12.5 lbs, on a T4 to get to 12.5 you are only losing about 2lbs.

Now on the machining end of lightening a flywheel, on a street car even performance you still want to see a good service life. I strongly recommend that you do not remove material from the backside of the friction surface. Doing so will risk warping of the flywheel, especially if you overdo it.
Really in lightening reciprocating mass (RM) it only makes sense to remove material from the outside of the fly. lt's also interesting that most street performance apps you want a counterweighted crank, thus increasing RM.

In the type 1 world it's highly recommended that you do not lighten a fly without counterweighting even the stock crank, but then you are removing more weight from the fly. It has to do with introducing harmonics, as the weight is also there to even out the firing pulses.
My Gene Berg 78mm counterweight crank set has a lightened 12.5lb fly, but then it also has a 6.5 lb pulley. So all told the complete assembly is close to stock weight, but it has a tighter center circle of the RM.
Original Berg stroker cranks are the holy grail of T1 cranks, I likely could part out my engine and get $3-4K just for the crank assembly on evilbay.