Inliners International Forums General Discussion Hi Performance 250 harmonic balancer problem

I went down and ran my car and the track this weekend and on the last run the harmonic balancer came apart. The outer ring with the belt grooves totally left the scene. It was a brand new pioneer balancer that i installed just 2 days before. I also have drilled for the bolt in the end of the crank. Is there a different balancer that I should be running. Its a early 70s 250 and the rpms only went up to about 6 grand.

Defects aside there are a few reasons why it might have come apart. The balancer shook itself apart from torsional vibration harmonics beyond what it was designed for or an out of balance condition in the engine. Drive belt or belts for the water pump, and alternator if you are running one, are too tight causing the pulley grooved outer ring to slip and eventually work itself off. A crank bolt through the hub wouldn't stop that from happening. It only keeps the hub assembly from backing off the crank snout.

There are one piece balancers that can be run on these engines. Some have a belt groove and some do not and require a bolt on pulley. I'm sure one of the racers like Twisted6 can give you more exact info on these.

You can install a Vector/Fisher damper.
They make one w/the v-groves machined into it.
Or you can install a Chevy v-8 damper ..but you will have to move all your accessories fwd, because they do not have the v-groves machined into them.
www.fisherconcepts.net
Good luck!
Hank
BTW... what were your times @ the track???

The best E.T. was 15.978 @ 87.981 mph with a 2.548 60 ft time. I could use some 4:10s in the rear and slicks but its an everyday driver. Plus maybe learn to shift a bit quicker. Ill check on the fisher damper.

Fisher makes a nice unit. The one with the belt groove is not for racing. To use any other one of two things need to be done Either cut a 1/4 groove into the timing gear, Or trim a 1/4 inch off the dampener. The fisher unit 71/4 does not need to be trimed. But No matter what route you go The pulleys will need to be moved to align things back up. Somethings else to also RECHECK if your flywheel/flex plate to see if it had come lose as well this could also be a reason the dampener came apart. If the flywheel/flet has come lose and you have them star washers on it REMOVE them. and Use loctite on the bolts.

how was the balancer installed? with a hammer then that could have been your problem.i learned that one the hard way.

"To use any other one of two things need to be done Either cut a 1/4 groove into the timing gear, Or trim a 1/4 inch off the dampener."

I installed an 8 inch SBC damper w/no mods to install it.other than moving all the accessories fwd.
I do not know why you need to cut a 1/4" groove in the timeing gear?
or the other step? Explain please. :-) Thank you.
Hank

The balancer was installed with a 2x4 being hit by the hammer so that it wouldn't damage it. Once i get another balancer on it ill see if the flywheel came loose again. On the fisher balancer i tried to e-mail and call them but the e-mail didn't work and the phone has been disconnected so Im not sure what is happening there. If anybody has a fisher damper for sale with the belt grooves or knows whats going on with fisher let me know.
thanks
Bill

You should really get a damper install tool. I think they are about $20.00.When you pound on the damper... you are also pounding on the rear thrust bearing ... not a good idea.
two cents worth.
Hank

I heat the balancers in a oven till they are 250 to 275 degrees, they they will slip right on or atleast 75 to 80% of the way. Joe

If the end of the crankshaft is drilled and tapped, use an installation tool. There is no way pounding on the end of the crank will help thrust settings. If it is drilled I would also recommend using a Stage8 bolt kit to help keep the balancer on tight.

Cutting the end off the balancer or grooving the timing gear is to get the balancer closer to the front of the motor and further on to the crank. It also helps make pulley alignment a little easier. I tend to like cutting the end off the balancer as it is extremely easy for any machine shop and hopefully the balancer will out last your timing gears.

when it comes to cutting either the dampener or the gear. If you tink about it It is better to cut the gear Main reason Being is NOW the dampener is now Held in place by BOTH Key ways Not just the front one. Heating a dampener I don't think would be very good for the rubber. This drys out what Oils are in the rubber In turn i would think shorten it's life.

Larry, the guys at that rebuild dampers todl me as long as I didn't go over 275* it would be just fine. Wouldn't want to do it alot of times, but it sure helped in my case. Joe

Well i got it all back together and I didn't have to use a hammer to install it this time. But does anybody know whats up with fisher dampers and there site plus phone number? None of it seems to be working right now.

As previously posted www.fisherconcepts.net
is working but it is Vector Dampers now.

One other trick that has been Used Mostly on the Vthings is to have another keyway cut. But it's not that cheap to have done.

I had the same problem w/my 250... loosining flex plate/flywheel bolts dampers coming loose, chewing up the front of the crankshaft where the damper goes.
I tried every thing... almost. I rev above 6000 RPM keep in mind.
The only thing that worked for me was I installed an 8 inch SBC damper.
Let me tell you... what difference it made!!!
Since then Flex plate bolts do not come loose, the damper has not had one problem & now the engine turns RPM quicker & higher w/the V-8 damper.
I just had to move all the accessroies forward to line up the belts.
Goodluck!!!
Hank

I thought dampers were motor specific. I looked on the vector site and noticed they arent. Now Im confused. I was going to get a new one for my 235, but dont know which one. Hank said his motor revs up faster and higher with the bigger damper, why would that be?

I bought the Fisher/Vector damper that Mike Kirby uses.He now uses different ones because Vector takes too long to make them. They are for Small block Chevy's.They do not make a specific one for a 194-292 damper... it is a V-8 damper.
The reason it revs higher & smoother is because it takes out more of the bad harmonics/vibrations.
If you are not going to rev it high a stock type damper is fine.
My engine is a different series than yours, so your engine may have different caracteristics/vibrations than the 194 - 292 engines have.

Hank

I've installed a 7 1/4" diameter SBC Fluidampr on my 292, I machined a pulley that fits over the damper, bolts to the face, and drives a serpentine belt. Will post some pics soon.