Solid roller camshafts spring pressure ?

Ok here we go I am building a BB for the street and strip,I am putting a large solid roller drag race cam in . Can I reduce the spring pressures ? I would like to go from a 551 rate to a 474 rate.

Sure, but will the valves float? Probably.

Best help, with the limited info given, is to do what the cam manufacturer recommends.

A number of things go into determining valve spring pressure requirements, lift, rate of lift, rpm, ect. None of which we have.

So what I suspect is if I lower my spring rates I must keep my r.p.m.'s down.without writing down tons of info?

Very generally speaking, yes, but there is a limit how low you can go.

Why do you want to reduce the pressures you have now? I've always been told(for over 40 yrs) on solid roller race cams by other hard core racers and the cam racers reps(not the 1-800 cam help) it is way better to have more valve spring pressures to start with than the minimum as new springs will loose presuure after being ran, raced and warmed up and cooled down when racing them Years ago I bought a Rimac 1000 lb. spring pressure checker due to being told by several different cam racers reps to set up all the good race valve springs up so they had between .060 and .080 on each spring before coil bind, if that meant that I ended up with 20 to 50 lbs more pressure opened it was okay as they would loose bewteen 20 to 30 lbs after 60 to 80 runs, which they would. I would recheck them after 100 runs or so and reset them up, on some I could add a .015 or maybe even a .030 shim and get them back to .060 from coil bind and raise the pressures up to or above the pressures recommended originally and get another 60 to 100 runs out of them before having to replace them The main thing I've learned on racing valve spring pressures on solid roller cams is to look at the back side, closing side, of the lobes, if there are no roller tracks all the way around the lobe, especially on the closing side from the nose for a short space down to the ramp, to raise the pressure so the roller couldn't hop or launch off the nose or top of the lobe and come crashing back onto the lobe further down from the top of the lobes On solid roller race cams valve spring pressure having more than what recommended is way better than a tiny bit to little

A "drag race" cam should be maxed out for best performance drag racing only... short run times. High spring pressure keeps it under control and beefy high end parts help it live for X passes... not extended street driving.

With the goal of "street/strip" I think a more moderate profile would help your engine live and make you happier. Something like an "endurance race" grind for example. It would also function well on the street and let you rev it with more moderate springs.

Weak springs will hammer the bearings in the tappets worse than high spring pressure. What are the cam specs? What is a "large drag race roller"? Specs?
Doug

This is right as any valve float or anything that can let the valves bounce or hammer on the roller lifter wheel is not good for the roller lifter. You want enough spring pressure to keep that roller wheel on the cam. Why not go with a street type of hydraulic roller as they run less spring press then what you have ? Ron

I agree Cab and that's what I do, use all available open pressure of the spring .080 before coil bind. Controlling the valve and spring from bounce or float is key to getting the most out of your valve train and not damaging it or the cam.

MLR426

Thanks for all the info,I will rethink this roller cam thing,it is in fact my first roller experience .iwas thinking that the high spring pressures would eat up parts.Oh by the way the cam specs are duration at .050. 252/256. Lift .627/.622. Las 105. ICl 101

If you alreay have that cam use it it will flat rock you back in the seat at WOT Put a good set of lifters on it and a very good set of valve springs (I like and use PAC springs now ) and pushrods with the pressure the cam company recommends and go have some fun That cam insalled at 100 to 102 ILC will sound really radical at idle and up to around 2000 RPM in gear