How clean should the INSIDE of upper and lower intakes be before installation?

[bcmbcmbcm]

Hey folks,
My upper and lower intakes are off the car, and I have them pretty clean and ready to paint up.

But when I run my finger inside one of the ports, it becomes slightly black with grime.

How important is it to clean this grime INSIDE the intake prior to re-installation? Does it get a little grimy from fuel and air after 100 miles any way?

And if it is important, how do I clean it?

Thanks in advance!

 

[Mustang5L5]

There will be oil inside there to some degree. If it's excessive, you will want to clean it and def take a look at your PCV setup.

To clean it, i've used simple green on stiff wire brush that I can fit inside. Submerge in a tub of water and scrub away. I've been able to get the lower intake pretty clean inside like this, but the upper one you can only do so much for obvious reasons.

I'd just get it clean enough to the point there are no loose particles that can flake off. Obviously, make sure the upper is free of water before you reinstall.

 

[5.0W/5.0]

I did my LT1 intake at the high presure car wash. It wasn't that dirty, but I keep on spraying until the water would come out clean.