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Thu Jun 19, 2003 6:18 pm

I have a 1600 type 1 motor with the original flywheel. I also have access to a metal lathe. Is it feasible to attempt to lighten this flywheel to about 13 pounds, and if so what guidelines should I go by? I don't want to compromise flywheel strength or end up with a piece that is going to flex. Thanks, Larry.

Thu Jun 19, 2003 6:53 pm

It's possible, but I would think more in terms of keeping it balanced, but I wonders if you would notice any change in the rev of the engine (Besides it slowing down quicker)

Thu Jun 19, 2003 8:48 pm

I've read that this should help the engine to rev a little quicker, as long as you don't lighten it much past 13 pounds. I should have mentioned that after the flywheel work (if it happens), I plan on having the flywheel, crank, all the rotating assembly "street" balanced (ex-rods to within 2 grams). All this to get a little more response from the motor on a budget. I never thought about it slowing down quicker, but that would make sense, too.

Fri Jun 20, 2003 11:19 am

from what i understand lightening the fly wheel is an old hotrod trick, higher and faster revs which will make the car more responsive and add a couple horse power. good luck with lightening it your self, but it really is not that expensive to take it to a machine shop and have an old pro do it. Just my opinion but then again if you do it yourself more props to you.

Sat Jun 21, 2003 3:56 pm

You should be able to grab the flywheel from the inside of the recess where the clutch goes. Make sure to use a indicator to insure that you have the flywheel in straight (if you turn it out of round it will be wildly unbalanced!)
Start taking cuts from the outside of the flywheel right up to the edge of the starter gear ring. You can take .050 passes no problem but make sure to keep the rpm's down under 500. finish of by turning the cutting head to hit at 45 degrees to clean the sharp edge that will be left. I've done five or six myself and it's a piece of cake.
NOTE: do not attemp to cut the clutch facing of the flywheel on the lathe. That you'll want to take to a shop with a flywheel grinder. trust me on that one!

Tue Jun 24, 2003 10:20 am

The pictures below are some examples of where you can cut.
http://216.25.126.221/mufflermike/584.jpg
http://216.25.126.221/mufflermike/585.jpg
the one on the left is an example of purchased off the shelf type flywheel. The one on the right is my old flywheel that was custom done. Notice the difference where the material is taken off. most of the material that was taken off my old flywheel happend on the outer edge. the farther out you can remove material, the more affective it is. the right one is actually closing in on 15 lbs, but acts more like a 14ish becsue of the location that the material is removed at. you can see, some material is removed under the starter gear and on the od of the main part, the left one has material removed from the back. this leaves a thinner surface and can allow flex when coupled with a real pressure plate.
then if you really want to get extravegant http://216.25.126.221/mufflermike/1063.jpg
you can swiss cheese it and bring it down into the 10 lb range. But this is way to much undertanking for most and is only really good for big high end motors.

But on to the subject of actually lightening flywheels. for a 1600, i think its not all that great a move to lighten one up.(my opinion). sure it will rev faster, but what does that give you. hp is still the same. yes it is rotating mass that hp does have to push, but not all that much. And if you are into drag racing starts, you would be better off leaving the weight to help push the car out.(unless its an ultra light car) But truly a user specific deal. not a general 12 or 13 lbs is best for all. the heavy flywheel came off of a 180hp 2332cc motor and when added with a berg heavy pully, actually produced better ET.s becsue it helped push my heavy car off the line. what was gained at the start far outweighed what was lost on the other end. As i moved into the alky and torque changed then i was able to loose the heavy pulley. Definitly user specific. I have a friend with a 1914cc in an almost all stock car. worked ok with the lighten flywheel. he went back to a completly stock weight unit and suddenly his car started to leave the line like it was suppose to and picked up a few tenths in ET. These are just examples, so maybe it might be wise to see if you can pick up another flywheel that you can widdle on, and take a little off at a time and see the affects, if its wrong, then you can go back to your original or make the original to the point of what you feel is best. Stock flywheels are cheap.