what spring pressure should a hydraulic roller cam? A friend of mine is running springs off flat tapper hydaulic cam on his hydaulic roller and i am thinking he has too low of pressure. He will be drag racing it some too. i am thinking he will float the valves.

Depends on the cam, of course. Most mild street roller cams will take about as much pressure on the seat as a flat tappet (figure around 110-130, give or take) but with greater open pressures.

The simple off-the-cuff answer is yes, he will likely float the valves.
The more correct answer was given by Damon: It depends.
The lifters are heavier and the ramps are quicker, so the likelihood of "launching" is rather high.

just curious how will a 150 shot of nitrous react with valve float. i am just wondering what will happen if he is running the nitrous and he floats teh valves?

just curious how will a 150 shot of nitrous react with valve float. i am just wondering what will happen if he is running the nitrous and he floats teh valves?
Nitrous doesn't cause valve float. Revs, and only revs do. It will run just fine to a certain rpm, then power will fall off dramaticaly, as the valves begin to bounce on their seats on closing.

just curious how will a 150 shot of nitrous react with valve float. i am just wondering what will happen if he is running the nitrous and he floats teh valves?

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i am just wondering if it wil explode or anything. i know i have to watch me car so i dont hit the rev limiter with nitrous.

Before you guys blow the motor up w/ the spray,MAKE SURE the springs are good. Fix the small problems before you make one big one and that lil mouse motor will be reduced to door-stop material faster than you can say "oh shit".

Your friend is running springs used from a flat tappet now on a roller,bad move. Whenever you change cams,you change to a NEW matching set of springs regardless. Dont have the money?? Then dont change the F'in cam. Sounds like your "friend" needs to figure out what cam he has and get a set of matching springs and then after that problem gets fixed and it runs good for a bit,then you can spray it.

i am just wondering if it wil explode or anything. i know i have to watch me car so i dont hit the rev limiter with nitrous.

click here for a better explaination (http://www.flixya.com/nitrous-explosion-on-dyno)

I don't think these morons floated the valves, but the results would be very similar.

i will be talking with him. i dont know why the springs were not changed.