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Re: [Fot] Subject: TR3 Cam Failure

To: fot@autox.team.net
Subject: Re: [Fot] Subject: TR3 Cam Failure
From: Larry Young <cartravel@pobox.com>
Date: Mon, 18 Mar 2013 12:03:08 -0500
Delivered-to: mharc@autox.team.net
Delivered-to: fot@autox.team.net
References: <96b.588233a5.3e77f62b@aol.com>
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130307 Thunderbird/17.0.4
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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