FORD 331 347 PRO SPORT SFI BALANCER 28oz DAMPER 6.61" EXT. BALANCED # 34269
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FORD PRO RACE BRAND SFI PERFORMANCE PRODUCTS 28oz DAMPER 6.61" FOR FORD ENGINES. EXTERNALLY BALANCED (WEIGHTED). PRO SPORT SFI SERIES
Pro Sport Series, made by Pro Race Performance Products. S.F.I. externally balanced, (weighted)
The above picture is a file photo. Apearance may vary.
6.61 INCH DIAMETER.
Lifetime Warranty, Unlimited Mileage, Street or Strip Use.
The PRO/SPORT ALL STEEL Harmonic Dampers are designed and manufactured for racing and high performance street applications and are available for a wide range of engines. The PRO/RACE Damper is a direct replacement for the cast iron stock damper which is no longer permitted by most racing sanctioning bodies due to the danger of fracture and high speed disintegration or separation of the inertia ring from the hub. This problem is eliminated with a PRO/SPORT Damper.
The PRO/SPORT ALL STEEL Harmonic Damper is also a must for all belt driven supercharger applications due to the additional torque loads on the damper hub and keyway, which results in failure in nearly 100% of all blower installations with a stock damper. PRO/RACE company now offers specific models for supercharged small block (#74265), big block Chevy (#74267), and small block Ford (#74269) engines. These special dampers include dual keyways and the Chevy versions also feature six tapped holes to accept most blower pulleys.
What is SFI Spec. 18.1?
The SFI Foundation, Inc. (SFI) is a non-profit organization established to issue and administer industry standards for specialty performance automotive and racing equipment. The SFI Spec. 18.1 provides a set of minimum requirements for manufacturers to comply with when producing crankshaft vibration dampers. The standards were introduced to ensure safety on the track where certain racing classes require a SFI certified damper as specified by the sanctioning body.
The SFI spec 18.1 stipulates minimum mechanical properties for the steel used in the construction of the damper, the requirement that the outer inertia ring is retained and where the damper is subjected to spin test requirements of 12,500 rpm for one hour. PRO/RACE and PRO/SPORT models conform to SFI Spec. 18.1.
SPORT vs STREET
ALL STEEL Dampers. The PRO/RACE company offers three styles of dampers for small and big block Chevys; a Race and a Pro Sport model as well as a Street model. The difference is that on the Pro Sport and Race models, the elastomer is bonded to the steel hub and ring. This bonding is particularly valuable on applications where sustained high speed is present, such as in marine or circle track applications.
The Street models are suitable for mild to moderate performance applications on engines making approximately 350 to 400 hp. The special splines (see cutaway photo) enhance the bonding between the elastomer and the inner hub and outer ring which helps prevent any outer ring radial movement, a common problem on OEM stock factory dampers.
If you would like to use a Street style damper on a 400 small block, simply combine our #64262 Street small block damper with our #65266 Counterweight, and you will have the proper combination for that engine. Cutaway shows internal splines, which provide for twice the contact area, eliminating any possible movement of the outer ring. External diameter of the inner hub is splined, as is the inner diameter of the outer ring. Elastomer is vulcanized to the splined areas on Race units. This forms a very positive bond between the elastomer and the steel with twice the contact. Note splines on hub and ring.
Extremely High Quality Standards
WE RECOMMEND YOU REPLACE YOUR DAMPER BOLT EACH TIME IT IS REMOVED, DUE TO THE STRETCH FACTOR. RE-USED DAMPER BOLTS CAN COME LOOSE. NEW DAMPER BOLTS ARE ESSENTIAL, IN OUR OPINION. USED ONES CAN ALSO BE VERY UNSIGHTLY ON YOUR STREET RODS.
Please see our other listings for additional accessories.
Part number 34269
FOR SBF, ext. bal. 331, 347
When identifying your existing damper (balancer), look on the back side. This is not visible if the damper is mounted on the engine. If your damper has no offset in the casting or weight, then you have an internal (neutral) style damper. If you do see the offset in the casting or a weight, you have what is classified as an external damper, commonly used on all 400 SBC engines.
Be sure of what you need before purchasing. You will definitely know if you have the wrong damper on the engine, as it will have a serious vibration. Remember, neutral dampers, have no weights or offset in the casting. They are perfectly balanced, hence the term neutral.
We recommend replacing the mounting bolt and washer when installing a new damper. We have them listed in our other auctions.
THE PRO/RACE LINE OF BALANCERS IS ONE OF THE BEST ON THE MARKET, AND IS USED EXCLUSIVELY ON ALL OUR IN HOUSE ENGINE BUILDS.
It's a very wise investment when building an engine to replace the balancer (damper). This is an elastomer type balancer, much like the ones from the factory. The principal component to their operation is a bonded elastomer ring which adheres to the inertia ring and hub, and they are far superior in design to the OEM stock dampers. If you're considering using your old, possibly original damper, then you should know there is a great chance the elastomer band has dry rot and is not adhering as it should to the inner ring and outer hub. If this is the case, then damaging harmonics are not dampened as they should be.
If your original damper is not functioning as it should, you will not notice it, as it has little to do with how much vibration is transferred into the vehicle. You simply can't base the condition of your damper on whether or not you can feel it in the car or not. It would be fair to say if your damper is more than 15 years old it is not functioning the way it should.
One more good reason to replace the damper is the poorly visible timing marks on the OEM damper. This makes it nearly impossible to set your timing properly. One feature about the Pro Race line of dampers is the highly visible timing marks. We find this priceless when it comes to setting timing on an engine. Your view to the balancer is often limited in most cars, and being able to see the timing marks is a must.
We have seen other dampers on the market for less money, and we have purchased them. We have found such dampers to be very low in quality and appearance, and the timing marks are hardly visible. These no name, low cost dampers could also break under high rpm if the metal is not properly cast. We also found the diameter of the center to be slightly undersized, requiring the need for broaching. Such dampers are being sold online from various performance car parts companies that appear to have no regard for the safety or function of the product.
When you receive your damper, you will notice the high quality appearance. We carry most of the Pro Race line, and consider them a first rate product.
A note from Skip White, president.
We have seen others market a knockoff, no name damper that has to be the worst product on the market. We have nothing against knockoff products, but some are worth warning about. These low quality dampers being sold by many have a poor appearance and the center hole is often out of spec, with a dull finish. The casting was not machine finished; it was rough cast, as you would see on an engine block.
What concerned us more than anything is knowing that the design of an elastomer style damper is very critical to how well the material is bonded between the inner and outer ring. This must be able to withstand the constant oscillation and heat for many years. The elastomer must be made of a material that won't dry out any time soon.
One more very important aspect of this material is its Durometer rating. The Durometer rating, or resilience, is very important, as it should be in tune with the crank harmonics or it will not be able to do its job properly. Knowing how much pride the Pro Race company takes in everything they make, we are confident this factor has been addressed.
When we're standing over an engine to set the timing, we usually have to rev the engine up to around 4000 rpm or more to make sure we get a total timing reading, as most distributors have very resistant springs in them. I would not want to think that I sold a damper that could develop a fracture or already have one in it, and know that this could break under high rpm, and whoever is standing above it would be at risk of death or serious injury.
As we mentioned, stay away from the no name, or ultra low cost dampers. A final note: get rid of that tired old damper on your engine. The elastomer ring is more than dried out, and is most likely not dampening the damaging crank harmonics. This can lead to fractures in the crankshaft. It is claimed that dampers that are not doing their job can cost horsepower. This is most likely due to the fact that the crank harmonics are not being dampened, and create a drag in the engine.
Harmonic Balancer, Crankshaft Harmonic Damper, Torsional Vibration Damper.
The term so often used for this component is harmonic balancer, which suggests the unit balances the engine. In general, this statement is misleading. A better description for this component is a harmonic damper or torsional vibration damper. This better describes the actual function of the unit.
Torsional vibration occurs in the crankshaft of engines, as a result of the combustion process, the sudden reversal of load on the piston, conrod and crankshaft during compression, followed by the ignition or firing of the compressed fuel and air in the combustion chamber. Subsequent relaxation of the load following combustion causes deflection or flexing of the crankshaft. This oscillating vibration which results from the reciprocating load changes will remain in force until dissipated by internal friction or damping. At certain rpm ranges these oscillations can come into phase with each other, creating potentially damaging torsional peaks in the crankshaft.
Unless the amplitude of these torsional vibrations is controlled, major damage can occur to engine components, such as rapid wear of the timing sprockets, stretching or breakage of the timing chain, pitting or cupping of the camshaft and lifters, broken valve springs and valve train failure, reduced service life of crankshaft bearings. In extreme situations uncontrolled torsional vibrations can lead to a loose flywheel or a broken crankshaft with serious safety consequences.
Why use a tuned elastomer (rubber) damper.
Elastomer harmonic dampers have been used exclusively by Automotive OEMs for car engines, no matter what brand of vehicle, be it local or imported. The reason is simple, they have found that a tuned elastomer damper is able to reduce destroying crankshaft harmonics more effectively and over a wider range of RPMs than other styles of dampers.
PRO/RACE, PRO/SPORT and PRO/STREET tuned elastomer dampers are also marketed as private label models by Ford Racing, Mopar Performance and others. These groups tested a number of aftermarket dampers including fluid or viscous style dampers prior to selecting PRO/RACE and PRO/SPORT tuned elastomer dampers which provide superior dampening for rapidly accelerating, high RPM engines.
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