--- On Thu, 5/14/09, EDWARD BARNARD <edwardbarnard@prodigy.net> wrote:
From: EDWARD BARNARD <edwardbarnard@prodigy.net>
Subject: Re: [Fot] Broken Cranks: Was - Any connection between these
problems?
To: "Norlin Engineering" <norlinengineering@comcast.net>
Date: Thursday, May 14, 2009, 5:55 AM
Jim: Five or six years ago we had a small journal 1296 that I built for Susan
break between the rear main and the flywheel. I believe the circumstances were
that it dropped out of overdrive at a very inopportune moment. The location of
the break caused loss of propulsion without any further damage internally. If
memory serves me correctly the engine was running it's strongest before the
mishap, and Susan was mopping the track with her competition when it happened
Do I remember correctly Susan and Brad?
--- On Wed, 5/13/09, Norlin Engineering <norlinengineering@comcast.net>
wrote:
From: Norlin Engineering <norlinengineering@comcast.net>
Subject: [Fot] Broken Cranks: Was - Any connection between these problems?
To: fot@autox.team.net
Date: Wednesday, May 13, 2009, 7:22 PM
Interesting to read this thread as I suffered a broken crank on my 1296
engine this past weekend.
This is a small crank engine, prepared to SCCA limited prep rules for HP.
Shift point is 6800-7000 and max revs are about 7500, so the engine is
really not stressed that much. The crank was balanced, but not nitrided or
shot peened.
The crank broke between the #1 con rod journal and the #1 main journal which
is totally weird. It's hard to tell looking at the two halves since they
beat on each other for a few seconds before I could kill the motor, but if I
had to guess, there was a fairly large internal flaw in the forging that
didn't show up on the magnaflux test.
I've been lead to believe that these cranks are virtually bullet proof, but
now I'm not so sure. How many others have suffered broken 1300
crankshafts?
The real bummer in this (besides the cost) is that I was leading HP in the
National when the crank failed.
"Helping to restore the economy thru racing" - Jim Norlin
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