[Fot] Subject: TR3 Cam Failure

[Catpusher at aol.com]

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 at autox.team.net writes:

Date:  Sun, 17 Mar 2013 22:12:49 +1100
From: "geoff byrne"  <gkbyrne at optushome.com.au>
To: "Friends of Triumph"  <FOT at 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