DeTomaso Mailing List: March 2000, Message #125

In a message dated 3/2/00 9:09:10 PM, Cars5244@aol.com writes:

<< Can anyone tell me if the balancing procedure is the same for an 
externally 
balanced engine as it is for internally.  I realize the balancer and flywheel 
are weighted for balance but is there anything else to know? >>

The main difference is in the location of the balence wts. External balence 
has off-center wts cast in the harmonic balencer and the flywheel as well as 
the counterwts on the crankshaft. Internal balenced motors have the external 
wts cut off and slugs of tungsten (Mallory-metal) pressed/welded into holes 
drilled in at least two of the crank counterwts. Bolt-on bob-wts are clamped 
to the crank assy and spun to a specific speed on a balencing machine; the % 
imbalence and its location is found via meter or by strobe, and more/less wt 
is added cut-and-try until a certain 'balence factor' is found by the 
machine. Internal balence is used by real-racers to counter the twisting 
force that results from spinning cast wts (external balence) at each end of a 
2-1/2 ft long crankshaft, at very high speeds. Internal balence also costs a 
ton more to do....Cheers- J DeRyke