So I purchase a bare b16 head on ebay, and I'm trying to piece it back together for my LS/VTEC build, I know I need to replace the valve stem seals, but do I need purchase valve guides? cause I see these bronze valve guides on ebay and other websites, cuz I thought the valve spring keeps the valve in place?

 

You usually don't have to worry about the valve guides unless something happened to the engine. If your gonna run stock valves then just keep stock valve guides. If you wanna put SS valves in then put in some bronze valve guides. It helps with the wear of the SS valves. Whenever you have the head put together just have the machine shop check the guides and see if there good. I'm sure they will be. I got a head off ebay and only two of the guides were still in. So I had to put new ones in.