ok i have a 305 HO motor that has been bored .030 over... the rings where gapped so i could run a 150 shot of NAWZ is i ever wanted to..... any ways i got a 350 on its way so i ripped out the 305... i'm going to be selling the motor to my buddy for his 89 jimmy becuase he has a cracked block... but i want to replace the rings in the 305 beucase it has really bad blow by.... i went to jegs today and say that they have drifferent size thickness for the riong so now i'm stuck on what size to get :-( can any one help?

 

You will have 3 rings on each piston to deal with. There are 2 rings (the top 2). On the bottom there is a oil control ring. They should be 5/64" for the first 2 and 3/16" for the oil ring. When putting the rings on the piston, it should go like this:

--TOP OF PISTON--

5/64" first ring

5/64" second ring

3/16" oil control ring

 

measure your ring grooves then you know what you have instead of guessing, if you don't know what pistons are in it. why would you want to order parts before you have it apart and inspected? you have no idea what you have or what you need untill you get it apart.