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
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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