I've been reading about lightweight flywheels for the SBC on the street and I've found something interesting. Most posts say DON’T do it for the street….what I'm referring to is running a 15lb flywheel on a SBC. My car, 69 Z, is a 400+ sbc with a TKO and 3.90 gear (high first gear ratio ~11:1 "street use only") After reading all of this bad or negative warning type information about the flywheels I was convinced that it wouldn't be a good idea to use it. However, I did weigh a Z/28 flywheel and a 396/427 flywheel I found it is appx 15lbs OEM!!!! Now, knowing info this I searched for Z/28 / 427 flywheel comments and I couldn't find ONE person that said get rid of the OEM flywheel and put on a 30lb aftermarket for the street. So how bad is the Z/28? The 302 has little torque, big cam, and a lightweight flywheel and it came that way. 396 / 427's come with a 3.75" stroke crank (same as 400) so there is a significant torque increase and it too came with a 15lb flywheel.

Bottom line: I own a 15lb McLeod flywheel and was planning on using it on my 406sbc street car. I'm willing to change it to a 30lb if I "really" need to and I honestly "don’t' know.

You'll be just fine with the light flywheel. The car will accelerate faster, decelerate faster, and will turn better. You can't store as much energy for the initial launch, but while the clutch is engaged the light wheel outperforms the heavy one. We used a 9# Fidanza and it worked extremely well.

Thank you - decision made

From my experiences, light flywheels can be picky on launches,
so for drag race stuff, needing consistency, it'd be tricky...like herky-jerky- if you get it wrong, by bogging at the line with too little gas, or with too much, spinning the tires at first, letting off- grab traction- bog- then take off as it recovers.
For street stuff, as soon as you're rolling, it's fun. Quick revs. Click through the gears faster.

I'd say get a light one and enjoy.
I know when I eventually change mine over to a manual, I'll put a light one on.

TKO and 3.90 gear (high first gear ratio ~11:1 "street use only")

IMHO you will be just fine, the 11:1 first gear makes it even better.
My windowed aluminum wheel only weighs 8 lbs, with a 12.8:1 first, there is no problem on street or strip.

---Bill.

[SIZE=2] However, I did weigh a Z/28 flywheel and a 396/427 flywheel I found it is appx 15lbs OEM!!!!

Don't know where you got those flywheels, but the stock/OEM Z/28 and BB flywheels weigh 28#.

:beers:

I run a CF 38 pounder on my car! Couldn't comment on performance cause I cant stop burning rubber!!!

I went aluminum FW, I like it.

I have the 10lb Fidanza aluminum flywheel with a 3.27 1st gear and 3.73 rear = 12.2. I have nothing but good things to say about using a light flywheel. Street starts are not a problem, the car can walk away from a stoplight with barely a hint of throttle. 2nd gear starts are not even very difficult. Besides freeing up horsepower, a quick revving engine is sooo much more fun, in feel and in sound. People think I have a lot more cubic inches than I do (350) because the motor just sounds so urgent. You can't be as lazy on downshifts though because the revs fall to idle very quickly when you're off the throttle with the clutch in.

Don't know where you got those flywheels, but the stock/OEM Z/28 and BB flywheels weigh 28#.

:beers:

part # 14085720 15lbs 3 oz on my scale. Have a few - maybe they were not 302 DZ motor flywheels? but I know these are old (cast) and one came off a sbc and another came off a smaller big block.

I did a search on the number it comes up under just about everything from 1955-1985 153 teeth that used the 10.4" clutch.

part # 14085720 15lbs 3 oz on my scale. Have a few - maybe they were not 302 DZ motor flywheels? but I know these are old (cast) and one came off a sbc and another came off a smaller big block.

I did a search on the number it comes up under just about everything from 1955-1985 153 teeth that used the 10.4" clutch.

That's an old over-the-counter GM Performance Part that SERVICES those applications, but it was never used in production. The production flywheel was P/N 3973452, casting #3791021.

:beers: