Today's race-bred engine is a highly advanced piece of engineering. A couple of grams here and there in the reciprocating department may not seem like such a big deal, but in reality, it can make or break a potent powerplant. Case in point:
A typical Sunday cruiser with a mostly stock powerplant won't care; however, in the world of big horsepower and upper-rpm-slinging street/strip cars, it makes all the difference in the world. These cars are making serious power, and keeping that mill together is all contingent on what's going on inside the block
A balance job isn't to be taken lightly. We are pushing the limits of physics, design, and rpm. Blend all those together and it leaves little room for error. Tolerances are being measured in thousandths of an inch, and pistons are weighed in hundredths of a gram. Any miscalculation here can lead to torched bearings, a sloppy-vibrating mess, or worse.
"There are certain balances for certain applications," says Mike Consolo of QMP in Chatsworth, California. He reiterated that its important to know what engine combination is being used in order to decide what type of balance to throw at it. Since this isn't something that can be done in the comfort of your own garage, it's important to find a machine shop that has the equipment and know-how to get the job done.
For this balance job, we delivered everything, including the crankshaft, pistons, rods, rings, and wristpins. Once there, Consolo took the reigns and steered this balance job into something more drag-race-worthy.
What We Did
Balanced the entire rotating assembly for our 540ci big-block.
Keep your bottom end buttoned up and spinning without a hiccup.
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How are the bob weights determined? It's simple actually. Consolo added all of the components together. He made sure to add the large end of the rods twice and the bearings twice since two rods swing together on each rod journal.
|Part ||Weight (g) |
|Piston rings ||69.5 |
|Piston ||583.9 |
|Wristpin ||173.6 |
|Piston locks ||4.8 |
|Piston rod ||229.8 |
|Oil ||4 |
|Rod bearing (x2) ||47.4 |
|Small end of rod ||162.4 |
|Big end of rod (x2) ||459.6 |
To get things started, Consolo unwrapped all the rotating components and began to weigh th
Next, Consolo matched the weights he had measured and added the bob weights to each of the
To obtain an accurate measurement on the balance machine, an angle finder is used to deter
Once all of the individual weights had been accounted for and the bob weights added, Conso
Starting at the rear of the crankshaft, Consolo centered-punched it to begin drilling. He
The Sunnen balance machine is a beautiful piece of machinery. It makes balancing relativel
Through additional spinning, it was learned that two more holes needed to be drilled to co
Every little bit helps. Creating a smooth finish on the crank's rod journals should also b
At QMP, no crank leaves the shop without its drill holes chamfered and properly cleaned. U
|PARTS LIST |
|MFG ||ITEM ||PN |
|JE ||Pistons ||257943 |
|Lunati ||Crankshaft ||BP429IN |
|Lunati ||Rods || 6385FM |
|Total Seal ||Call || Call |