What size of inlet is normally on a I6. I got the valve and hose plus the brass vacuum block off of a 300 but the block thread was too large for my manifold so I took the existing block which had a Plug threaded in it and replaced it with one with a tube that I silver soldered into it. Here's the thing I had to use the inlet line from the 300 block that went to the power brakes it was the only one that fit tight into the hose I got with the pcv valve but I was positive it was on the next size inlet as a matter of fact it had to be. When I have the car running and pull out the valve from the valve cover there is so much vacuum that the valve whistles. So I'm thinking that perhaps I should put in the smaller size tube up in the hose to act as a restrictor.