Looking at ISKY tool room valve springs # 9905. What's a good seat and open pressure for Hydraulic Roller Cam. #9905 is 165 LBS on seat and 450 LBS open.

i use them on every engine i put a hyd roller cam in,bump the seat pressure up to minimum of 175 lbs.

How many hours are these springs good for with a .6" lift hyd roller cam?

Thanks, what retainers do you recommend? Also what open pressure for hydraulic roller?

we usually use comp cams steel retainers for marine engines,just set the seat pressure,the open pressure will fall into place.

my guess,250 to 300 hrs

I just rebuilt my motor and that's what my guy used for me and he knows how fussy I am and how hard I run.

Just a little of my thoughts on spring types and pressures.
First, its important ,especially here on engine tech here on OSO not to get to generalized on spring types and spring pressures. The spring choice should always be a factor of camshaft size and characteristics. Even in hydraulic roller camshafts, lift, duration and lobe profiles can vary a lot especially in custom grinds. Things like camshaft ramp rates, jerk and acceleration can have a major effect on whcih spring to run and what spring pressures to use.
Second the size and weight of the valves, size and weight of other valvetrain components such as retainers, pushrods, rocker weight over the nose, etc. will require different spring sizes and pressures. Valve stem sizes and overall valve stem lengths will need to be considered when choosing springs for an endurance marine performance engine as they effect the valve weights.
Lastly, the type of engine being built such as normally aspirated versus boosted and the rpm limit ranges and operating ranges will also need to be taken into account.

This being said, I and others know that the Isky Toolroom springs being discussed here are great parts with excellent reputation and great results when properly applied.

I just wanted some of the other OSO readers to realize that their is no one valve spring fits all and that there should be a lot of expert advise and carefull engineered selection process used in spec'ing and applying various size, spring rate and spring types in selecting a particular valve spring for any marine performance engine. Keep it simple but keep it particular and applicable to the actual use.

We always need to remember her on OSO that a lot of general novice marine engine builders and users read these threads a little to literally and may use this information to select their valve springs without taking more important selection criteria into account.

Best Regards,
Ray @ Raylar