What is this called & how do i get a replacement?

[FatBoyM]

This is the gasket in top of my cylinder head holding a air filter for the oil.
The engine is a blue print 383, I'm trying to locate a replacement or a better option. The gasket/bushing is breaking down, some of it has fallen into the head, should I be concerned about that?

 

[fourwheelerjeff]

it's a PCV grommet; you should pull the valve cover and get the rubber pieces out before they block oil flow and could potentially damage your engine

 

[Blue85]

Grommets like that are kind of standardized for aftermarket valve covers, i.e. not make or model specific. You should be able to get one at the local parts store. The rubber in the engine won't smash anything, but it could lay in a drain-back hole and make the oil pool up in the top. I suppose if it crumbled to tons of pieces they could plug the oil pickup.