stud sized

My father in law basically built my engine for me but with out asking him how do i know what size they are. I want to go up to 1.6 `rockerks but dont kn ow tnhe stud size. And asking him isnt a good idea because I mjust had the engine done and he doesnt think i should be doing mods so quickly.

Stock size is 3/8".

stock 305? stock 350? what about my 385 its just a variable?

For a stock LT1, I didn't look at your sig.

Measure the diameter of a stud.... only way you'll ever know what he actually used. Many engine builders will upgrade to 7/16".