Is it necessary to balance the engine when building? How do you know if it has to be internally or externally balanced?

I obviously know very little about this. Have read up a little and understand how it would effect if parts were way off internally, but still in the dark.

Is this something that drag/race engines require because of the high compression? For an every day road beater could i get a way from doing this?

Thanks

If you dont care about longevity, little extra power, smooth running and so on. Then Detroit Balance is for you then.....

Bottom line. Its well worth the money to do so. Whats a $150 when you have spent more then that to build one...... I wouldn't cut that corner if it was me! JMHO

"The Poor Mans 427"
http://www.fordification.com/poormans427.htm

"The F.E. Wiki Home"
http://fordfe.wetpaint.com/


Wes Adams FORD428CJ
Built Ford Tuff With Good Ford Stuff
03 F-250 Crew Cab 4x4 6.0 and 35's
64 Falcon X-Ram 428
55 FORD Truck 4-link Rides on air with X-Ram 428
2000 Yamaha V-MAX VMOA#4277
2000 Yamaha 700 Mountain Max
2001 Polaris 600 Edge X
2001 Polaris 500 SP

And its been just fine....

"The Poor Mans 427"
http://www.fordification.com/poormans427.htm

"The F.E. Wiki Home"
http://fordfe.wetpaint.com/


Wes Adams FORD428CJ
Built Ford Tuff With Good Ford Stuff
03 F-250 Crew Cab 4x4 6.0 and 35's
64 Falcon X-Ram 428
55 FORD Truck 4-link Rides on air with X-Ram 428
2000 Yamaha V-MAX VMOA#4277
2000 Yamaha 700 Mountain Max
2001 Polaris 600 Edge X
2001 Polaris 500 SP

Some engines, such as most 4-cylinders and V-twins, vibrate even when optimally balanced. It has almost no effect on longevity, though the shaking does consume some of the gasoline energy, since the energy for shaking is stolen from the combustion event and not delivered to the crankshaft as is desired. Instead, the lost energy of the shaking engine heats up motor mount insulators, heats up shock absorbers, and rattles sheetmetal and plastic parts.

A 90-degree V-8 is one of the few engine designs which can be perfectly balanced, so that even a slight imbalance will be noticed. One reason a slight V-8 imbalance will be noticed is the motor mounts of a V-8 engine typically aren't designed to handle as much vibration as engines which naturally vibrate. Also, the sheet metal "bolt ons" of a V-8 longblock are also typically lighter duty, as they are designed to be mounted to a low-vibration engine, and so they may lack some extra supports or grommets normally used in 4-cylinder and other engines.

If you can handle the very slight loss in horsepower and fuel mileage, there is no real need for balance. Just be sure it is not so imbalanced that the vehicle is aggravating to drive. A badly balanced engine can add all kinds of creaks to a car over time.

Shoe.

I feel it does add to longevity and here is why:

Balancing goes hand-in-hand with performance engine building. Balancing reduces internal loads and vibrations that stress metal and may eventually lead to component failure. But is it worth the time and effort for mild performance applications, everyday passenger car engines or low-buck rebuilds.




http://www.centuryperformance.com/engine-balancing-for-life-power-amp-efficiency-spg-145.html

http://www.babcox.com/editorial/ar/eb10330.htm

http://www.eddiesvalvegrinding.com/balancing.htm



"The Poor Mans 427"
http://www.fordification.com/poormans427.htm

"The F.E. Wiki Home"
http://fordfe.wetpaint.com/


Wes Adams FORD428CJ
Built Ford Tuff With Good Ford Stuff
03 F-250 Crew Cab 4x4 6.0 and 35's
64 Falcon X-Ram 428
55 FORD Truck 4-link Rides on air with X-Ram 428
2000 Yamaha V-MAX VMOA#4277
2000 Yamaha 700 Mountain Max
2001 Polaris 600 Edge X
2001 Polaris 500 SP

When I think of the proverbial Ice Skating Gal spinning and pulling in her arms and spinning twice as fast it wrecks my comprehension of ballancing an engine.
The engines balanced by weighing the individual components. That piston that weighed 260 Grams has no weight at all when there's an exploding mixture on top of it and on the next stroke its sucking in mixture making it change weight. The piston that was balanced at the top of a 6.35" stroke is going to weigh a bunch different at the bottom of the stroke
Then my predictive Maintenance customers have shown me how balanced components go through two distinct critical rpm zones where vibration goes haywire. And Ive read of racing engines that are decidedly out-of-balance at low RPM to mid range and extremely balanced at mega high RPM. I can't imagine ballancing a tire on a car where the 1/4 pound wheel weights moved in and out 6 inches.

Whether balanced or unbalanced, internal loads are about the same.

There are a number of errors in the first link, but the important thing is it does try to present the information in a factual manner.

It mentions "loads at RPMS", and shows the hundred or so extra pounds added to the bearing load if unbalanced by a paticular gram amount (or maybe subtracted if light by that gram amount) to the bearing load at 8000 RPMs. It fails to note that at 8000 RPM the bearing loads are probably over 10,000 pounds (I'll avoid the math details), so the bearing load deviation is maybe one percent. That's not going to cause any measurable additional wear.

It speaks of internal imbalances that cannot be felt, but that is hogwash. If it cannot be felt at the exterior of the engine, the engine is simply balanced. The V-8 engine is wildly imbalanced inside, even when perfectly balanced on the outside. Take a look at the center four pistons and you'll note they have no significant nearby counterweights. These individually imbalanced internal forces do "balance out" when you take the engine in it's entirety. In fact, there are eight pistons which are all improperly counterweighted individually, but when taken as a whole engine, each piston leans on all existing counterweights and all seven other other pistons to summarily balance out to near zero when looking at the whole engine from the outside. The bearing loads are simply affected less than a percent in an imbalanced engine assembly.

Lost power, lost fuel mileage, and lost comfort are the drawbacks. Any engine that is built for racing near it's limits must be balanced to be competitive on power output, but for a grocery getter, the issue is not always significant. If replacing the pistons in a grocery getter, weigh the old and new piston assemblies to make sure they are similar. If so, then you are probably good.

JMO,
Shoe.

IMHO it should be balanced

read up on centripetal force

before re building my "low" miles 428, there was extreme vibation within the engine as the rpms increased.

Besides a very rough rebuild with poor clearances, the rotating assembly was 60 grams out of balance.

at 4000 rpm, that equates to 40-60 lbs of out of balance rotating mass. The higher the rpm, the more mass.

It costs $150 to balance an engine's rotating assy. What doe it cost if you tear it apart.

On mine they included the flywheel and pressure plate all as part of the rotating assembly