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Author Topic:   Harmonic Damper ???

Posts: 21275
From: Reno Nv USA M&M#1240
Registered: Apr 2001

posted 01-23-2002 01:19 PM     Click Here to See the Profile for Fastymz   Click Here to Email Fastymz     Edit/Delete Message   Reply w/Quote
Ok I think a damper gives balance to the crank.But why do some people say they have a 50.oz damper and other will say they have a stock one.So I like to know exactly what a damper dose and How,and Why you pick one.There are so many diffenrent kinds out there too.My stock looks ok for now.If I did replace it which should I use.Sorry for all the questions but,I feel this is the only place to get the facts.


65 coupe,351w,RPM intake,Carter625,shorty headers,2.5 exhaust, Flowmasters,C4,open 8" 2:80,Big Boss 429 hood scoop,Crager SS,Black Suede.

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Daniel Jones

Posts: 898
From: St. Louis, MO
Registered: Aug 99

posted 01-23-2002 02:42 PM     Click Here to See the Profile for Daniel Jones   Click Here to Email Daniel Jones     Edit/Delete Message   Reply w/Quote
The crank, flywheel, and balancer are a matched set. Ford has used two different
balance factors: 28.2 oz-in (289's, 302's, 351W's, and 351C's) and 50 oz-in (5.0's)
on its small block V8's. Note the units (ounce-inch). The balance factor is a
combination of a mass and a distance away from the crank centerline. Some racers
will neutral balance (also called internal balancing) which, in the case of small block
Fords (some engines are neutral balanced from the factory), involves adding weight,
typically in the form of high density Tungsten-based Mallory metal, to the crank and
removing the balance factor from the flywheel/flexplate and balancer. Weight out on
the end of the crank introduces stresses that neutral balncing reduces. Some
builders prefer some amount of balance factor on the crank snout, others prefer
neutral balanced. All (that I've talked to) agree that 28.2 oz-in is better than 50 oz-in.
Many stroker kits are balanced to 50 oz-in becase it takes less of the costly
Mallory metal and is compatible with stock 5.0L balancers and flywheels/flexplates.
If I were doing a stroker, I'd hold out for 28.2 oz-in. BTW, Late model 50 oz-in 5.0L
cranks had a reputation of breaking in A Sedan racing.

Dan Jones

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Just Strokin

Posts: 754
From: Tuscaloosa, Alabama
Registered: Dec 2001

posted 01-23-2002 03:20 PM     Click Here to See the Profile for Just Strokin   Click Here to Email Just Strokin     Edit/Delete Message   Reply w/Quote
The real purpose of a damper is to dampen the harmonics (ringing) of the crankshaft with the up and down movement of the pistons and rods. Like Dan mentioned, they do have to balance the cranks assembly for the rods, pistons, etc and come up with the 28.2 oz or the 50oz imbalance.

My thoughts are that Ford engineers felt the 50oz imbalance on the crank with the correct damper and flywheel gave for a smoother engine for the passenger cars and trucks.

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