Hi bill....i just asked my friend/machinist about it...The ford cam is a
cast cam...which if traumatized previously could cause it to break...
another reason could be mis-alignment of a cam bearing
Racer Bud
----- Original Message -----
From: "Bill Bartlett" <BillBartlett@wingnutracing.com>
To: <edwardbarnard@prodigy.net>; "FOT" <fot@autox.team.net>
Sent: Saturday, May 16, 2009 10:19 AM
Subject: Re: [Fot] Fw: Re: Broken Cam
> Speaking of broken cranks, I just had a cam break in my just rebuilt 109E
> in a
> Lotus 7. (1498cc 4 banger, push rod, modest cam etc....) Won the race but
> lost
> the engine.
> I have heard of lots of cranks letting go due to lots of reasons but not a
> cam. What are the likely reasons and does this happen more then I know.
> Bill B
> Lotus 7
> GT6
> Etc...
>
> -----Original Message-----
> From: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] On
> Behalf
> Of EDWARD BARNARD
> Sent: Thursday, May 14, 2009 6:56 AM
> To: FOT
> Subject: [Fot] Fw: Re: Broken Cranks: Was - Any connection between these
> problems?
>
> --- 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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