[Fot] TR3 Cam Failure

[Stutzmans]

As time goes by we tend to forget some of the old lessons.  Except Hardy who 
is right on.
TR3/4 cams were designed by the factory with the diameter of the front half 
larger than  the back half.  This stopped the problem of cam deflection.
When cam grinders regrind these cams they have to remove some of this 
increased thickness or the new lobe heels would be below the shaft.  Could 
deflection return on these cams?
New blanks - I recently bought and installed a 270 from BPNW ground on a new 
blank by David Newman in England.  This new blank, presumably from India, 
did not have the factory increased diameter front half.  Could deflaction be 
a problem?
Because of stories that the dizzy gear on new Indian made blanks was not cut 
properly causing dizzy shafts to break, I test installed mine with die 
makers blue and it was ok.  Could deflection have been the problem?
Bruce
----- Original Message ----- 
From: "geoff byrne" <gkbyrne at optushome.com.au>
To: "Friends of Triumph" <FOT at autox.team.net>
Sent: Sunday, March 17, 2013 7:12 AM
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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