Well, I posted this in the 4.6 General Discussion, but nobody responded. So I figure maybe you guys would know better, since you deal with mainly just 4v's. I'm just gonna copy and paste my post from the other section.

-----

OK, my question here is how much better are stainless steel valves than stock.

This is on a 99 4v C head. Mine should be here this Tuesday.

I talked to MMR about porting, and they said with Comp springs and ss valves, I'll be good to around 1000hp.

So my question is how important are the stainless valves? Is it a power thing? Or an RPM thing? I'm gonna be putting some CMS custom grind cams in, for a N/A and big shot of nitrous setup, spinning to around 8k. Obviously I won't spin that high on a stock shortblock, though.

But I keep rambling. Do I need stainless valves? I'm definately porting the heads and putting the springs and cams in before I put them on the car. But are the valves necessary? I'll have it all apart again eventually when the shortblock goes in, so could I do the valves then? I'm trying to get the car running by June 1st, and not doing the valves saves me like $400.

 

YEs I would do both springs and valves. If your doing your heads and cams you mine as well. They are mostly an RPM thing. If you have your car set up for running out the RPM's and don't have them done you will end up floating that valve and will cost you a lot more in the end.

 

I'm not gonna be spinning to 8k though, until I get a shortblock that can handle that, too. I'll still be going to 5800, maybe 6k, something the stock short block can handle.

So would you still say I'd need them now? I mean, if I have the extra money, I'll get them, but if I can save $400 I will.

 

5800 would be fine, but I still wouldn't beat on it everyday. Not saying you would. So it all comes down to $. If you want to save it now thats fine, but it'll cost more in the long run to have your heads taken apart again. If you're experienced and doing the work yourself then I would wait.