intake castings

[Glenn Briglio]

Originally Posted by Adger Smith

OK, here is what my friend JV Brotherton (Owner of Brodix) told me when I was complaining about port size/Vol matching specs.
As the molds are used the ports shrink due to the wear on the mold.
I'm not a mold maker so I took him at his word. He said the early part of the production run will be on size and the tail end will be smaller.
I was hoping someone that knew the mold process at GM would take the bait and tell us. I hope that helps. BTW I always flow the manifolds to be sure.

Wouldn't the ports be bigger if molds wear and get smaller?

[SSDiv6]

Originally Posted by Glenn Briglio

Wouldn't the ports be bigger if molds wear and get smaller?

No. As the intake runner pattern wears with use, the runners get smaller and more material surrounds the pattern.

[Ralph A Powell]

With wear the sand core gets larger therefore a smaller port

[curtis reed]

Originally Posted by Ralph A Powell

With wear the sand core gets larger therefore a smaller port

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.

[SSDiv6]

Originally Posted by curtis reed

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.

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.

[curtis reed]

Originally Posted by SSDiv6

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.

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