The article that mentions the reason for enlarging the front part of the
cam sites deflection as the primary issue they were trying to solve.
Deflection leads to tossing valves, valves bouncing off the seat, etc.
Making it larger up front helps both problems, strengths and flexibility.
On 3/17/2013 11:46 PM, Catpusher@aol.com wrote:
> If the camshaft shaft diameter is reduced during re grinding,
> that(between #1 and #2) is where it is most likely to fail. If you are
> unlucky, it
> will also fail in front of the #2 cam journal, and the cam piece will fall
> down and trash the motor.
> The USA factory race cams were ground from cams that arrived in the USA
> with un ground lobes, and KAS had them ground. I have had the lobes of a
> standard cam (TR4A is best) welded before regrinding, and that worked. In the
> development of the TR2 they arrived at the two shank diameters in each
> camshaft to reduce failures.
> I also strongly recommend checking all possible related issues: from coil
> bind to the dist/oil pump gear and the cam bearings.
>
> TR Regards,
>
> Hardy
>
>
>
> In a message dated 3/17/2013 11:02:59 A.M. Pacific Daylight Time,
> fot-request@autox.team.net writes:
>
> Date: Sun, 17 Mar 2013 22:12:49 +1100
> From: "geoff byrne" <gkbyrne@optushome.com.au>
> To: "Friends of Triumph" <FOT@autox.team.net>
> Subject: [Fot] TR3 Cam Failure
> Message-ID: <001801ce2300$5e5230e0$1af692a0$@optushome.com.au>
> Content-Type: text/plain; charset="us-ascii"
>
> Amici
>
> I have been helping a friend with his TR3 race motor and we keep braking
> cam
> shafts . recently the cam broke between 1 and 2 cylinders while holding
> 5000
> rpm through a sweeper. Comments seem to indicate that the 4 cylinder motor
> is prone to breaking cams and a steel billet is required . I would
> appreciate any comments on a similar experience and solution
>
> Geoff Byrne
>
> TR6 Racer Down Under
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>
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