List, re Harmonic Balancer question, and V8 balance, some more food for
thought. The good old Ford flathead V8, 1932-53 (R.I.P.) never had any
harmonic balancer, and still doesn't. It has the same crank
configuration as all the billions of later OHV V8s, EXCEPT for having
only 3 main bearings, and (I suspect) a more rigid crankshaft as a
result.
Flathead V8s are famous, as are all V8s, for natural good balance and
vibrationless running. My reading suggests that OHV V8s use (and should
use) harmonic balancers (actually 'dampeners') because it helps to
control and reduce the flexing and twisting end-to-end of the crankshaft
which otherwise may lead to early fatigue cracking and failure.
P.E. Irving is his book "Automotive Engineering" tells us that the V8
engine should be viewed for balance purposes as a set of four 90 degree
vee-twins, and a 90 degree vee-twin has inherently good vibration
characteristics, so what vibration is produced tends to be dampened by
the counteractions in the other parts of the crankshaft.
One intriguing fact is that the crankshaft, rods and pistons assembly
produces all the vibration and before it can be transmitted into the car
through the engine mounts, the said vibration has to go through the main
bearings into the massive and heavy block, and excite a response in the
block. The inertia of the block itself has a tremendous dampening
effect.
All this helps to explain why big-block, huge-power V8s are able to be
rigid-mounted in race cars and some street rods without much vibration
being noticed by the driver, and without breaking the mounts.
With the above, I am assuming that your merely rotating pieces, clutch,
flywheel, torque converter, pulleys, crank hub, etc are in correct
balance. If not, any or all of them can create quite a bit of obnoxious
vibration. In addition, if you have a 'detonation' condition in the
engine under load, rather than proper smooth combustion, the shocks of
this can create their own vibration in the block.
Cheers, ArdunBill
|