does a datsun necessarily need a cold start valve?
If the cold start is removed then it will have a hard time staying running with a cold engine and get worse as the outside temps drop,it may not even start at all cold. So to answer your question you need the cold start.
@tennisshoes they told me i can bypass it.thats why im asking the question.but thank you for you answer it helps me out as well
My '77 280z didn't need one. The CS valve is a piezo-electric injector on our cars. When my valve started to leak many years ago I took the valve off and plugged the orifice on the intake manifold. tennisshoes has a completely valid point though...my car stays in south Texas where temps below freezing are rare and of short duration. The Bosch ignition and fuel injection system is bomb proof and fine w/o the CS valve in S. Texas winters.
so without it it wont be able to start in cold weathers?
It may start but you will have trouble keeping it running until the engine warms up some, it will most likely try popping back through the intake. It all depends on how cold your climate gets.
well i live in the antelope valley so in the winter it gets really cold and the summer really hot but i have another question on the same subject...without the cs valve would it do any damage to the car?
It won't hurt the motor while you seek a replacement and install before Fall season.
would it be good to buy a new one or a used one?
Personally I'd go new; $80 is nothing compared to a car that won't and need re-troubleshooting/fixing the issue again.
where can i find a cheap one?
i ripped mine out. only useful for very cold weather starts. and even without it you can still start, just might take a bit more cranking.