OldCarBum

I'm building a 496 big block to drop in to my 73 Coupe.
I'll be running 10.4 to 1 compression ratio, Crane hydraulic roller 230/236 @ .050 598/610 lift 112 lsa camshaft, Edelbrock Performer RPM oval port aluminum heads, Edelbrock RPM Air Gap intake, Quick Fuel Q-850 carb, MSD ignition, headers and other additional goodies, in front of a TKO-600 close ratio 5-speed.
I always ran lite weight flywheels in my drag boats and was wondering about any advantages or disadvantages of running one in my 73, which will be used for street use on foothill and coastal winding roads and highway use.
I'm building my 73 as a hot rod and don't really care about fuel economy.
What do you think or what is your experience with lite weight flywheels?

terrys6t8roadster

The 6t8 SBC got treated to a Fidanza 11 lb flywheel. It allows the engine to accelerate and decelerate mucho faster, RPM matching is very easy, the performance gains are excellent. That said, for street driving the loss of the heavier flywheels momentum requires attention to the vehicle speed. The engine very easily gains or looses RPM. It's been on the back of the engine for 8 years and never needed a clutch adjustment. T

Gordonm

bence13_33

OldCarBum:
I ran an aluminum one on my last 468, it seemed to rev quicker, though it is tough to gauge because I went from 10:1 to 11:1 compression and switched heads. I did notice the bottom end was a little more soggy (which again was definitely due to a different set of heads). The aluminum flywheel doesn't have as much stored momentum from my understanding, so taking off from a stop light will be a little more difficult than with a heavier steel flywheel that has more stored momentum. The lighter flywheel I think would be fun once you have the RPMs and are upshifting and downshifting. I do feel like it was able to rev quicker with less effort once I got moving.

69427

Run a stock/heavier flywheel. It makes life easier at stoplights, and helps the idle quality.

I run a lightweight flywheel and pressure plate, but I do a lot of track days and have pulled every ounce I can off the car.

cagotzmann

The only issue I have with the light weight flywheel with the addition of a T56 magnum . Mcleod RST Twin Disc + Ram 2530 Aluminum Flywheel is gear rattle noise within a RPM Range on acceleration only.
Have a listen
This is because a twin disc doesn't have vibrational dampeners in the clutch discs.
When I had a single disc it made no noise that I could hear.
Now its not as noticeable ounce you cover up the console, but you can still hear it.
Will the TKO 5 speed have the same problems with a twin disc + light weight flywheel, I don't know.
I have a 3.08 diff with a 2.66 first gear and I don't have any problems driving on the street.
I found with the light weight flywheel the car just performs better for the activities I use the car for. Road Track days.

gkull

I'm am pretty sure that Fidenza doesn't sell the 11.5 pound aluminum 168 tooth fly wheel any more. I think that on my next tranny pull my 11.5 pound aluminum is coming out and my 22 is going back in but I have lite weight everything 6.250 ati damper, March aluminum crank pulley, and lite weight crank shaft sbc

I have 26 inch tall rear tires, 4.11 rear end, and. 64 OD tko600. I'm only tacking @2700 rpm at 80 mph so my motor just purrs along on the freeway

Your total rotating mass is way above mine so you need to find the lightest flywheel available, sticky modern tires, and good 14 inch rotors on the front

JVetthead

This was my fidanza.. Kinda scary when I found this. Of course it was on an LS7 on my C5 road race car that was set for 7200 rpm, but still...

gkull

That is the exact reason why I don't think that Fidanza makes the 11.5 pound anymore. People were running high pressure springs in the pressure plate and if you are dumping the clutch or keeping the gas on speed shifting the drive line shock was cracking the aluminum centers. It is not the rpm, it is how you shift. I saw it every day out at the track. people not even attempting to rpm match gear shifts.

JVetthead

I always made an effort to take it easy on my drivetrain, never have done a clutch dump or power shift, and with over 10 yrs of road course was pretty good at rev matching. Point is that flywheel was not abused by me.
After this I went with the 7" quartermaster and well, that's a whole other can o' worms.

gkull

Sorry for assuming that you were slamming the clutch and cracked it. Which quarter master did you go to, the1,2,or 3 disk. I always felt bad for multi disk clutches just driving from the transporter through the crowds to get to the hot pits to strap the owners in

what class are you running something like T1

DUB

On a street car I keep it original heavy flywheel

On a car that I am going to drive with a butt load of spirit...then I would go with a lighter flywheel.

If I am driving it competitively...then I guess I would take it to the level needed to keep up with the pack due to any advantage is a good advantage.

So for me it all depends.

DUB

JVetthead

I think it was the 3 disk,its been a few years.. Awesome clutch once you got the car rolling! but getting it rolling was usually embarrassing.

I built the car for st1 (nasa) but decided to hang in TT1 and when the water cooled wallet guys showed up with sequential trans I had to draw the line and have been out of it for a few years.

OldCarBum

cv67

good move on going steel

PAmotorman

the 65 396 corvette was the only car from the factory that came with a light weight 15# iron fly wheel. that is why they were so quick.