Valve gear to suit cam

[davemoni]

Hi,
Have an L98 which has had a cam only installed. Wanting to change springs, push rods at a minimum. The cam has .550 lift, intake duration 233, exhaust duration 237. Seem to be a lot of different spring set ups available. Anyone got any advice on what is good and what is not so good and how much seat pressure is needed for that cam. Dont really want excessive seat pressure if not needed. Is it worth doing the rocker trunnion upgrade or just go with roller rockers.

 

[monstar]

Use high quality beehives for 0.550".
View media item 250These are the common springs for that spec. Not much in it, I use PAC1511 with same lift, VVT.
View media item 339I think the main consideration underpinning bearing shock and arm stress is cam choice: base circle vs prime circle (lobe lift), and lobe pitch curve (ramp rate); spring pressure; and god harmonic stability at different orders of peak operating rpm.
View media item 333GenV geometry has the larger base circle, leverages lift with higher rocker ratio so to safely use AFM deac lifters at peak RPM.
View media item 251I use Yella Terra 1.85 ultralite rockers mounted on paired shafts to that same end.
Setup tested on Spintron for minimal distortion vs stock, good for 640hp daily no probs at 200k miles.

 

[davemoni]

Thanks for that info. Read somewhere standard spring is about 105 lb seat pressure closed and 300 lb open. Seems those beehive ones you have highlighted in that graph will do the job for my cam lift. Beehive type, I assume would have less reciprocating mass as well.

 

[DarkCrystals]

I prefer dual springs, just my opinion. Just a bit of insurance if the outer brakes the inner will stop the valve from falling into the bore and killing ya engine..