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Discussion Starter · #1 ·
I have a turbo grind solid roller with 650 lift and they are asking for 240-260# on the seat and 700-750# on the open i was thinking thats a lot for a motor that will never see more then 6500rpms. Can i run a with less seat and open pressures if i am only using 14psi ?
Thanks
 

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I would think an N/A solid roller cam would need as least 180-200 on the seat. If your intake valve is only 2" in diameter, that's almost 3 sq in of area, multiply that by your 14 lbs of boost and that's 42 psi working against closing the intake valve. Add that 42 psi to the 180-200 base pressure, and you're at 220-240 lbs on the seat. You're better off to have too much pressure than too little. With too little spring pressure you will break valves, lifters and rockers. With too much pressure you probably won't break anything. I hope this helps.
 

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That sounds ok . I like to run more than you need because even if the cam appears to be on the small side i have seen time and time again that people will spin the engine harder because the power is there......
 

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That sounds ok . I like to run more than you need because even if the cam appears to be on the small side i have seen time and time again that people will spin the engine harder because the power is there......
Just keep in mind that springs will lose some pressure over time. Mine started out life as 200#'s @ 1.800 and 525#'s @ 1.200, checked them now and there 170#'s and 450#'s respectively. Funny thing is it was going to 8k under 30psi like this and never skipped a beat.
 

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Thats not crazy low but i like alot of pressure mine is like 380 on the seat and 700 over the nose . I put the best spring i could find and when we checked them this winter i set them for what pressure we lost . If that is the spring he has with that low lift and not spinning it to the moon it should be ok. i would not go out and buy new springs not unless he has money to throw away.. Just my thoughts
 

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Discussion Starter · #6 ·
thanks everyone that helps a ton the intake valve is a 2.05 nmraracing how long/how many passes did it take to lose that spring rate? Is it common for the spring to loose that much rate over a year or so?
 
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