ok what do u need to make 4♥s in partners hand? and opps to hold?
There are a lot of things pard can hold. I estimate that about half of them give good play for 4♥, so you should bid it. If pard has the typical preempt, say,
xx
KQJxxxx
xxx
x
game is ok. Besides, it may very well be opps have a spade game and might chicken out of it.