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Author Topic: Valve Seat Pressure  (Read 630 times)

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ltank

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    • CVO1: 2000 FXR4 S&S V111, CustomS.S. 2-1 exhaust, Primo-Rivera OD 6 speed, 49mm Custom Front End Ohlins 30mm Fork cartridges , Hyperpro Shocks, Barnett Scorpian Clutch
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Valve Seat Pressure
« on: December 07, 2019, 04:52:42 PM »

S&S 640 cam does not list the required seat pressure
Does anyone know what's required for that cam? S&S
Only list one setting for it's high lift Springs.
  Question. If a 650 spring kit is used for a lower lift cam of 600 lift will it lower the seat pressure?
The Powerhouse 595E  cam has a 595 lift but requires a 180 lb seat pressure. It has almost exact same timing as the S&S 640 Cam. Main difference between the two cams is the .045 difference in lift.
To my understanding the higher lift is only helpful at the top end performance . At top dead center there's very little difference.  I hope it is easy on the valve train.
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HD Street Performance

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Re: Valve Seat Pressure
« Reply #1 on: December 11, 2019, 04:40:45 PM »

No specifics but an S&S cam vs a Woods or Sifton are all very different. Lift rates drive spring pressure as does the weight of the valves, springs and retainers. Follow the manufacturer's recommended pressure and be sure there is adequate clearance to coil bind at full lift. Clearance from retainer to seal is also important.
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