>Further to your concern about proper
springs, I recently installed three-
>part valve springs in my TR3A engine along with new tappets,
push rods and
>a 280 degree cam ( and some other things). The springs tested
>105# cold. Within 1500 miles both the cam and the tappets
>I've gone back to stock springs ( from Moss) which tested
at 76 - 79# cold.
>At operating temperature, these values should degrade - -
perhaps to aprox.
>70#. Time will tell if this setup will endure.
>Triumph Register of Southern California
The most likely reason that your cam and lifters went bad is
that the lifters were not hard enough. We hardness test ALL lifters
that we use in our engines, especially NEW ONES. In the last 2
years I returned at least 10 lifters to the TRF that were under
Rockwell 50 hardness. I have also returned many to Moss that were
too soft. Original lifters were always harder than 53 and sometimes
they went as hard as 57. I have received some new ones that checked
at 19! The criterion that we use is 50 to 53 for a stock engine
with stock spring pressures, 54 and above for anything with higher
spring pressures than stock.
For a full race engine with 135# on the seat and 225# or more
at full open we sort out sets that check at 56 and above. We also
have all our cams ground with tapered lobes to match the radius
on the base of the tappets. The original stock cams did not have
a taper and that contributed to their early failure.
We have not had a cam or tappet failure that I am aware of in
the last 15 years . Of course we always is Molybdenum disulfide
assembly lube paste on all tappets and lifters.
Regards, Greg Solow
Also: The factory spec for cam shafts is a Rockwell hardness
of c90 or above.
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