I'm right there with you, Daniel.  I couldn't have said it better!

I'm too soon old . . . and too late smart!   

Regards,
Charlie Brown


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Wow. What a revelation.  An alum. flywheel (much like multiple carbs) was typically a standard ‘hot rod’ speed equip. upgrade back in the 50s., and usually considered merely a trade-off of street-ability for max. acceleration.  Now after all these years, it’s finally revealed as possibly only good for circle-track racing? I’m dumbfounded.

6 VOLTS/POS. GRD. NW INDIANA

Thank you all for the information. Plenty to digest. Worse case I can sell the flywheel and afford the McCloud Clutch.
Richard

Back in '63 when I was racing my street/strip '56 T-Bird, I installed an aluminium flywheel because I was leery of cast iron 'wheels exploding at high rpm.  Stock class rules required stock flywheels, so I was cheating then.  The next year NHRA allowed any flywheel, so I was legal again.  I was convinced the aluminium wheel was quicker in the 1/4, but probably only in my mind.  It was liveable on the street because of my 4.55 Studebaker rear gear and T85-OD transmission.  The Bird is now street only with the same 4.55/T85-OD with a stock iron flywheel.

John - "The Hoosier Hurricane"

I will add that you will see aluminum flywheels in boat applications.  Only a small part of that has to do with boats not needing a clutch to put the prop into motion.  The major reason for an aluminum flywheel in a boat is for overall weight reduction which improves buoyancy and overall weight balance of the boat.
 
The horsepower attributes of an engine do change with the use of heavier versus lighter flywheels but not in the direction you would think.  When going to the dyno competitions, the flywheel weight is taken into consideration knowing that heavier flywheels will tend to improve the HP numbers, not the other way around.  On jet boat applications, heavier flywheels help to increase the rpm capability of the engine thus helping the top end mph numbers.

Lorena, Texas (South of Waco)

Linking to Mummert's ford-y-block.com site from here, he lists an Aluminum fly wheel at 15 LB. & 2  steel units at 26 lb & 32 lb..


Paul

The very first thing you need to ask yourself when buying/building a vehicle is, "What do I want it to do?" If it's a build, then ask yourself, "How am I going to get there?" Unfortunately, people often miss their goal by buying parts that don't work together. Even something as simple as an air cleaner can set you back if it won't allow for a carb spacer, or it doesn't provide sufficient space between carb vents and the lid, or you can't close your hood. Even when you've done your homework, sometimes things don't work as you expected. This forum exists, so we can share what we know, and ask when we don't know. 

By the way, I have a never-been-used air cleaner/w two elements that will either go to someone in need or taken to a swap meet. Fortunately, it's a small investment, not worth the cost/effort to return.

Ted.  THANKS for coming in on this topic.  Your and other Forum members' willingness to share their knowledge and experience have enabled me to pursue numerous y-block changes and modification with positive success without the pain of trial and error and the frustration of spending money and losing ground doing something!

Thanks to all who make the time to participate in this Forum!  

Regards,
Charlie 


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Great information Ted. Now i know why my other vehicle falls on its face unless i keep the rpms up. 

Located in Harford County Maryland 

The rule of thumb for a street driven vehicle is for the flywheel to be 1% of the car weight.  If the car weighs in at 3200 lbs, then the flywheel needs to be in the neighborhood of 32 lbs.  On a street driven vehicle with an aluminum or light weight flywheel, the engine rpm must be up more to simply get the vehicle moving versus what you see with a heavier flywheel.   As Charlie B. brings up, aluminum flywheels can be finicky to drive on a street vehicle.
 
While an engine may seem to be more responsive when winging the throttle with an aluminum flywheel versus that of a heavier flywheel, once you throw the total weight of the vehicle into the equation the actual acceleration characteristics do not change much.
 
Aluminum flywheels do shine in those instances where ‘take off’ is not a major concern such as in circle track or oval racing.  In a circle track vehicle, an aluminum flywheel does slows down that vehicle much quicker as a result of not having to shed the stored energy that’s would be in a heavier flywheel.  A good launch or take off becomes increasingly more important where clutch take offs are common such as in drag racing and/or just typical street driving.  This is where a heavier flywheel becomes much more important.  Getting back to Daniel’s question, if a vehicle bogs off of the line when taking off as in the case where an aluminum flywheel is used, then that becomes too much to overcome even with what seems to be a faster revving engine in a short period of time such as in a drag race.  But as I mentioned earlier, the weight difference between an aluminum flywheel and that of a heavier steel or cast flywheel is minimal and it will be unusual if that difference is as much as ½% of the vehicles total weight.
 
A case in point is a FE powered ’67 Comet I use to drag race; 4 speed with 5.14 and 5.43:1 rear gears.  With the aluminum flywheel the car would pull both front wheels off of the ground when launching but would immediately lose engine momentum and fall flat in performance after that initial launch.  When a 50 lb flywheel was installed, it would not only pull the wheels when launching but would carry them though most of low gear and then pull the wheels again on the second gear shift and/or rebound.  The ET for the 50 lb flywheel was quicker than the aluminum flywheel which goes back to that bogging scenario killing the 60’ times which are so important in drag racing.

Lorena, Texas (South of Waco)