lightened flywheel

C

calvin amerson

Member
i recently acquired a lightened flywheel, during an engine purchase my question why lighten what is the purpose, will it help or hinder performance, what are advantages vs disadvantages, thanks for all input
 
Hi Calvin, Two reasons for the 62 lb flywheel (stock) are: 1. The extra weight serves as an impulse dampener for the non-counterweighted crankshaft; 2. the extra weight allows "set it and forget it" ignition timing in the lower compression antique engine.

When to lighten the flywheel? 1. When the engine has a counter-slung (balanced) crankshaft where impulse dampening occurs directly under each cylinder; 2. When the compression ratio is raised significantly.

Please note unintended consequences of 2. above: If you raise the compression ratio and lower flywheel weight, you will need to play with ignition timing while you are driving, or add a centrifugal-type timing control to your distributor. Some of the guys have complained that they lose power on the hills with the lightened flywheel, but I have found that is not at all the case. But I do have to fiddle with the spark lever until I find the "sweet spot" for climbing a hill with my own '29 roadster (counter-slung crank, 5.5 head, and 40 lb flywheel).

I'm sure that some of the other guys will have something to add to this...

Happy Motoring! Chris
 
You don't say how much it's been lightened. I think the amount is important. In the days of Mod. A s, a 63 lbs FW was more useful than today. Gas wasn't as good, roads were rougher. speeds were slower. Engines needed to store the energy. Today the energy needs of an engine are different. A lighter flywheel means that speeding up the engine doesn't sap the same energy from the piston stroke, but conversely, 40 lbs of rotating iron doesn't store as much energy as 63 lbs. So it's a trade off. I have lightened my FW to 53 lbs and I'm quite satisfied with it.
Terry
 
talk to some one you trust try your local model a car club if you take to much out the car will not climb hills.Most guy do this when they put in a V8 clutch it makes the clutch a lot easer and does make the car faster if the right amount is taken out!!
 
Neil Mylar LakewoodCA said:
Does anyone know how much the Model B flywheel weighed?
Click to expand...
Well, we don't know, Neil Buddy, Dog:cool: here,
But wunce Ol' Bill finally lugged a Model A one on the bathroom "fat" scales, BUT kuldn't read the #'s on it?? I tole him to hold it & stand on the "fat" scales & subtract his "fat" wate frum the sum uf the weights-----Then he FELL DOWN!!!!!:eek::eek::eek: & got FREE Dog:cool: licks on his "TOOTH MARKED" fingurs:(
Buster T.:cool:
 
I believe that if you pull some weight off the flywheel you will lose RPM a little faster when you let off the gas, this helps get into a higher gear a little quicker.
 
Thanks to everyone that replied, don't how much it was lightned, or if engine was balanced, estimate approx., weight at 40# don't have scales, have not dccided to use it or not this is to be an extra engine in case of????????? again thanks guys for the input
 
My flywheel-clutch-pressure plate assembly is 20# lighter than the original. Works good for me.
 
Neil Mylar LakewoodCA said:
Does anyone know how much the Model B flywheel weighed?
Click to expand...


Neil,

Vince Falter's site says 53 lbs for Model B flywheel.


Quote:
"Pictured above is the stock Model B Ford flywheel at approximately 53 pounds. Note the difference in section and the two machining steps on the OD. The Model B flywheel is smaller to fit inside the Model B flywheel housing and oil pan extension.
A stock Model A flywheel cannot be used with a stock Model B housing and oil pan. However, a stock Model B flywheel can be used on either a Model A or a Model B."

URL from Vince's website:

http://www.fordgarage.com/pages/flywheels.htm
 
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One thing that has not been explained as a reason for such a heavy flywheel is, Henry being the egotist he was, figured anyone buying a Model A would be a previous customer or a new car owner. That being said, previous customers would have been accustom to the Model T which had a planetary transmission and used a clutch pack which only worked in high gear. He used a heavy clutch so that you could just drop the pedal and not kill the engine and the car would go. This sounds horrible but if you had never used a single disk clutch with a sliding gear transmission, this would have been common.
 
Vince,I just weighed a couple of my crankshafts . The 1928 beaver tail crankshaft weighes 25 lbs. The later model A crankshaft weighs 30 lbs. I used bathroom scales and doubled checked with my fish scales. The scales may not be exactly correct but there is a five pound difference. The beaver tail crank is five lbs lighter. Both cranks had the timing gear in place.
 
Just a note from experiance. In the early 90s my daughter drove her 31 tudor 350 miles from Prince George to Kamloops with one stop for gas in 7 1/2 hours. The flywheel had 20# removed , the crank was counter weighted and the whole assm. was balanced to within 1/2 gram. Rear axel was 3:54. We drove that old car almost every day for the next 7 years untill it was sold to a fellow model A guy.
 
bathroom scales being what they are, I weighed a std grind beavertail with crank gear at 30 lbs..

My scale usually weighs me 5 lbs light (compared to the one at the doc's office). The crank showed 28 lbs on its own. I held the crank and weighed both of us, then set it down, weighed meself , subtracted my weight and got 30# for the crankshaft.
 
Vince,

Model B "pinned weight" crank.

no gear and no woodruff key :D
Note: NOT drilled for pressure oil.

56.8 LBs

weighed on a $200 shipping scale.

quick measurement shows:

1.986 main #1

1.851 rod #1

Benson
 
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BEAVERTAIL crank

has gear ...

has woodruff key

29.2 lbs

weighed on a $200 shipping scale.

Too cold to measure main and rod size.

Fifty years ago an old time racing guy told me that this was a good crank for a racing engine!

He said with a big smile: ;):

"The Beavertail crank cuts through the oil vapor easier and has less air resistance!!

I took that to mean that he was joking! :cool:

Benson
 
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Benson said:
BEAVERTAIL crank

has gear ...

has woodruff key

29.2 lbs

weighed on a $200 shipping scale.

Too cold to measure main and rod size.

Fifty years ago an old time racing guy told me that this was a good crank for a racing engine!

He said with a big smile: ;):

"The Beavertail crank cuts through the oil vapor easier and has less air resistance!!

I took that to mean that he was joking! :cool:

Benson
Click to expand...

Anything that reduces oil friction in the crankcase means more hp at the output flange. One of the big reasons for dry sump oiling.
Dry sump = 15 hp gain.
 
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