Subject: Re: [Fot] Subject: TR3 Cam Failure

From: [email-masked]
Date: Mon, 18 Mar 2013 00:46:35 -0400 (EDT)

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,  
[email-masked] writes:

Date:  Sun, 17 Mar 2013 22:12:49 +1100
From: "geoff byrne"  <[email-masked]>
To: "Friends of Triumph"  <[email-masked]>
Subject: [Fot] TR3 Cam Failure

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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http://www.fot-racing.com

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From: Larry Young <[email-masked]>
Date: Mon, 18 Mar 2013 12:03:08 -0500

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, [email-masked] wrote:
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