i know alot of people go to the machine shop but i really want to know how i changed spring before but not on high peformance. i know my current springs are 1.950 installed height. with the cam swap comp says to have 1.900. so all i have to do is install the spring and use a valve spring height micromter to make sure im at 1.900 and do simple math right? but do you measure from the seat to the retainer or under the retainer do you have to measure from the retainer to the tip also. i also heard you lose spring height after brake in so would 1.910 be fine how much over or under is acceptable. if i come in at 1.950 with new spring i would have to have the head seat ground right. if anyone knows can it be explained idot proof. i am mechanicly inclined but not book smart.