Re: intake castings
 

That doesn't sound correct. If the core box that they use to make the cores was getting worn then the core would be getting larger. The core is what makes the plenum and runners, so they would also be larger.

Re: intake castings
 

In sand casting, the core box and the core are two different items.

For an intake manifold, the core box (drag), contains the sand and the intake runner core (mold). When the intake runner core wears, it reduces the dimensions of the core. That is the reason why many times you have core shift on new intakes, requiring further machining to make them fit on the engine.

https://www.meskan.com/Uploads/Images/Olds455Intake.jpg

Re: intake castings
 

Gotcha thanks. We run thousands of castings through my shop each year and obviously I am confused about what I thought I knew. LOL