Depends on the cam and accelerations the valve train needs to deal
with as well as the weight of the valve train components. For the
Larry Young Dx-298 cam, 100 lbs seat pressure is recommended. I run
to 6500 plus with that (although generally shift at 6000) and don't
see much evidence that it's too low. Less than that and I see an
imprint of the foot of the lifter on the base of the cam lobe on the
closing side indicating that things didn't stay in contact.
Regards, Tony
At 01:55 PM 2/14/2017, timmmurphh--- via Fot wrote:
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>I have 85 lbs. pressure on the intake valve with the valve closed
>and it sits at a height of 1.655 inches. At .400 lift, I have 190
>lbs. of pressure. We only run to 6000 RPM with the gearing we have
>and the engine we have. The valve springs are double springs and
>the machine shop says they are all about the same, very
>consistent. What pressures would be recommended? The machine shop
>thinks these pressures are light for a 6000 RPM engine. Any advice
>will be appreciated. Thanks.
>
>Tim Murphy
>1961 TR4 #317 BRG
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