How do you balance a V8 internally?

[SteveSS]

I've always heard of balancing and blueprinting an engine but I'm not sure I really understand it. I've seen drill holes on a crankshaft before but it wasn't on every counterweight just one or two. Is that for balancing and why would it be important as most engines seem to get away with not doing it? And what the heck is blueprinting?

 

[moparsaver]

Read Hawks thread for an Excellent explanation on balancing.
HawkRod is doing the 2023 Hot Rod Power Tour!

 

[toolmanmike]

I've always heard of balancing and blueprinting an engine but I'm not sure I really understand it. I've seen drill holes on a crankshaft before but it wasn't on every counterweight just one or two. Is that for balancing and why would it be important as most engines seem to get away with not doing it? And what the heck is blueprinting?

The balancing is done on a machine. The piston and rod assemblies along with the rings, pins, circle clips, bearings etc. are all weight matched. The rods are weight matched as well and end for end so all are equal. All the weight for one piston is called the "bob weight" and is added to the crank throws with a fixture.. The machine measures the out-of-balance weight (like a tire balancer works) and mallory metal is added to the crank counterweights to make them heavier or drilled to make them lighter. Here's a pretty good video of the process. Part 1 and Part 2

 

[toolmanmike]

I've always heard of balancing and blueprinting an engine but I'm not sure I really understand it. I've seen drill holes on a crankshaft before but it wasn't on every counterweight just one or two. Is that for balancing and why would it be important as most engines seem to get away with not doing it? And what the heck is blueprinting?

Blueprinting is machining and assembling the engine to factory specs. Every surface is checked and machined as needed for flatness, parallel and alignment. Everything is made as perfect as possible. Factory machining and tolerances were not perfect.

 

[HawkRod]

Read Hawks thread for an Excellent explanation on balancing.
HawkRod is doing the 2023 Hot Rod Power Tour!

Thank you! I'm glad if people enjoyed the pictures and descriptions!

I've always heard of balancing and blueprinting an engine but I'm not sure I really understand it. I've seen drill holes on a crankshaft before but it wasn't on every counterweight just one or two. Is that for balancing and why would it be important as most engines seem to get away with not doing it? And what the heck is blueprinting?

So as @moparsaver said, please feel free to cruise into my thread where I cover many details of my 500 stroker build.

Balancing:
Engines from the factory are balanced due to mass production techniques. But why do you want to balance? Well, you have 8 individual pistons that are very quickly moving up and down at different times. If they were a dramatically different weight, you could even destroy the engine due to vibration and forces put on bearings and internal parts. However, most imbalances cause an engine to not run smoothly; it will vibrate and cause harmonic vibrations, especially at speed. So when you balance an engine you make all the pistons and rods the same so they put equal force on the crank and bearings. This makes for a smoother running engine, gets rid of vibrations, is easier on parts and likely puts less wear on parts as well.

Blueprinting:
Blueprinting is where every aspect of an engine are checked and made as ideal as possible. One example is the deck height of our blocks. In many cases, their machining was done poorly at the time due to filings from other blocks messing up the pins that aligned the blocks. This means the bore length on one side of a block may have been different than another side of the block by as much as .015" of .020". So one aspect that blueprinting covers is measuring the deck height and then cutting the block so all the bores are exactly the same. Why would you care? Well, if one bore is .020" longer than another bore, then the longer bore will have less compression than another bore. It will make less power than the other bore. This again causes an imbalance in the way the engine runs, reducing its overall power and also ability to handle high RPM running.
So blueprinting is making sure every aspect of an engine build is checked and made exactly as it should be.

Bottom line is a balanced and blueprinted engine will make more power, do it more smoothly and have better longevity.

 

[SteveSS]

Thanks dudes.