In a message dated 8/25/04 2:02:37 PM Pacific Daylight Time,
tarch@bellsouth.net writes:
<< 2. I have a totally unsupportable notion that my crankshaft failed
because
of fatigue caused by harmonic flex. Several years ago I installed a radiator
fan and simply unbolted the old iron one. This left that 6" snout wiggling
out to the front of the engine. Was that a mistake? Should I install an MGB
harmonic balancer? If I have the crank, flywheel & clutch balanced before
installation, will this obviate the malevolent harmonic potential?
On the other hand, now that I am down to a raw block, the temptation to
forget economics and put together a bullet proof bottom end is pretty
tempting.
I look forward to your comments.
Richard Taylor
TR-4
Atlanta
>>
Richard -
I feel I must throw my personal .02 cents worth in here...
I ran for several years using far too many revs far too many times for the
ole tractor motor. The fan was removed as well as the extension. I made and
installed my own large metal glob up there at the front end of the crank which
allowed a bit more clearance up front. The mass of the home-made piece was
about
the same as the factory mass. This worked well for me. About 2 years ago I
decided that perhaps I should use a "real" vibration damper on the motor, and I
purchased on of the "MGB" type metal/rubber dampers. I had it balanced and
fitted it to the motor. 2 races later coincided with the end of the season and
scheduled freshening. At that time I found that the front main bearing cap was
cracked thru the 2 front plate holes. As this is not unknown, I replaced the
block. The crank checked out ok. I spend quite a bit of time massaging the
front
main cap to alleviate this problem to the best of my abilities. The new block
lasted through Saturday practice before the front main cap broke in two. This
time the crank went with it.
I cannot catagorically state that the "MGB" style damper was the cause,
however I now use a custom built ATI damper and have had no more problems.
Breakin up is not hard to do...
Nick in Nor cal
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