what does it take to install bronze valve guides?

[aribert]

I have a '78 200 head that I am going to pull to have it milled to raise the CR up to about 9:1 I'll hog off on my mill and then let the automotive machine shop do the final cut. W/ only about 65K miles on the head, it is not really in need of being rebuilt but I figure since it is off, I might as well have it rebuilt. I presume the cast iron valve guides on the head are integrally cast in place - correct? So does the machine shop bore the old guides out and them press in new bronze ones? I am planning on using teflon or vespel valve seals so I want to turn the end of the guides in my lathe (for retaining the seals) prior to the machine shop installing the guides.

Another question - anyone machined out the cast iron guides and pressed in the bronze ones themselves? Not that I am consiering doing this but I do have a mill.

 

[bubba22349]

I presume the cast iron valve guides on the head are integrally cast in place - correct? So does the machine shop bore the old guides out and them press in new bronze ones? I am planning on using teflon or vespel valve seals so I want to turn the end of the guides in my lathe (for retaining the seals) prior to the machine shop installing the guides. Another question - anyone machined out the cast iron guides and pressed in the bronze ones themselves? Not that I am consiering doing this but I do have a mill.

1. Yes the org. guides are part of the casting and than were machined to correct size.
2. Yes now days many guides are replaced with a bronze guide.
3. Since you have a mill you could probably do the job. After you have head setup in your mill its just boring the old guide out to correct size (slight interference fit), than you can use an air gun (Chisel) with a guide driver to push guide in.

 

[CNC-Dude]

You will also need a rollover fixture to rotate the head to the correct angle to bore the old guides out. Another alternative is bronze valve guide liners. It can be done on a workbench, but needs specialty tools to ream and broach the liners. There not overly expensive to do but the tooling can be if you are just doing one head to justify it.