norvalwilhelm

I started with a balanced engine and flex plate. I later switched to a flywheel which I had balanced by the original shop. They checked the flex plate then match the flywheel to it. After installing the flywheel I noticed that at 2700 rpm and again at 3500 the motor shuttered slightly passing through these rpms.
I bugged me so having nothing better to do I removed the flywheel cover and left it off. I removed the oil filter. I then divided the flywheel in quarters or every 90 degrees. I did this by marking a tooth, counting out 42 teeth, this is a 168 tooth flywheel, and marking it with magic marker to make sure all holes would come out in good locations. I then did it accurately a second time using a punch and marking exact locations of holes every 42 teeth 5/8th of an inch in from the ring gear. I then carefully drilled and tapped 1/4 inch threaded holes in these 4 locations.
I then made a 1 ounce weight from a piece of brass 3/4 inch diameter about 1/4 inch thick with a hole drill for the 1/4 inch bolt plus a counter sunk head. I weighted this on a postage scale I have.
I also numbered the holes 1 to 4 by stamping the flywheel. I then reistalled the oil filter and it is easy to get at the holes from the starter side to install weights.
I then bolted the 1 ounce weight to hole # 1. I got in the car, started it up, place my forehead on the steering wheel then slowly brought the rpm up watching the tac. The shutter running through the motor changed its rpm. On my 2nd attempt I just moved it to hole #2 and repeated the proceedure. I felt absolutely nothing to the test rpm of 4600.
I have driven the car for a week like this and often run it up to 4500 slowly trying to feel anything. Smooth as anything.
I will sometime move the weight to 3 and 4 locations to check it out but for now hole #2 smoothed out this slight shutter.
When I have nothing better to do I will also make different weights and try them in hole #2 and see if this is better.
This does not replace balancing an engine. Mine was balanced extremely carefully but when I changed flywheels it was not perfect. This just allowed me to fine tune without pulling the entire motor apart and redoing.
For those with a slight shutter someplace and nothing to do for an afternoon this could solve that anoying tremmer.
Just thought I would run this past you so maybe someone else could try it if all else fails before tearing into the motor.
Have a nice day

burners

Not bad, I'm impressed. That's a huge time saver when compared to rebalancing the entire engine. You should put this is the tech tips section.

MasterDave

Hehe, that's pretty good but if it's a 327/350 the flywheel is neutral balanced as opposed to the externally balanced 383/400 engines. I suppose the clutch/pressure plate could have been out and you fixed it by this method. If you replace the clutch it may be off again. When I was a punk kid I put a big '57 Olds V8 and auto tranny in my old '53 Studebaker pickup. :eek: I had to cut & weld the drive-line. It was WAAY out of balance, to the point of blurring your vision and seeing as I only had abut $4 to my name in those days, I just jacked up the rear end, opened the door, put it in gear and set the rpm's at like 2000. The door vibrated so much you couldn't see out the side mirror. :D I got under and let the drive line hit a piece of chalk, shut it off and hose clamped wheel weights on the opposite side of the chalk marks. Took about a half hour, about a pound and a half of lead and the door was butter smooth. The truck drove great. :cheers: The only problem was when a clamp worked its way loose and tossed a couple of weights off. :eek: Sounded like a bomb went off inside the cab when a couple 3 or 4 oz wheel weights would hit the fuel tank at light speed and then the truck would darn near jump off the ground 'til I got it slowed down.......I got used to it but it sure would scare the bu-jeebus outta the hapless passenger or two. :lol: :yesnod: Gawd I loved the 60's!!! ;)

norvalwilhelm

It doesn't matter if it's neutral balanced or not this is just trying to take that shutter out of it. And yes my pressure plate was checked before installation just to be sure. I replace a flexplate with the flywheel and suppositly they were of equal balance. The pressure plate what bolted to the flywheel as a final check to make sure it didn't through the balance off.
Alot of balance machines don't spin high enough to make the harmonic balance work with the fluid balancers.
This method of sticking a small weight as trial and error is just to try to make everything perfect.
I tried to get my driveshaft balance and they can not go past 3500rpm and yet when the engine is running at 4000 or 5000 in overdrive at .68 I am well above that. Here again a slight tremor runs through the car that I want to get rid of.