Got my parts for my head and cam install and I have a question, I got the 1.6RR from comp, what size stud do they take? Also, what size studs come on lt4 heads.

 

Comps can come in either 3/8 or 7/16. As far as the Lt4's read this.
Both the LT1 and the LT4 Heads accomidate 7/16" studs but the LT4 has larger 7/16 rocker studs. (top threads) The LT1 studs are 3/8" on top and 7/16" bottom. pt#3921912 for 7/16" and pt#1255216 for 3/8" LT1.