Sorry for bugging in. @Pᴀᴜʟsᴛᴇʀ2 have you tried some brass drift? Brass or another soft metal to prevent damage to the stem. Perhaps heating the head could free the valves?

I'm going to suggest something that makes use of mechanical advantage

@Martin - Yah, I've been beating on it with a brass drift ... didn't touch it. The problem with the head is, the guides are cast iron and have rusted. What is left of the valve is stuck in the guide. I need to break it free. I've been pounding on the broken end of the valve to push it free one way, so I can pound it out the other. It isn't moving. I'm doubting my Vise-Grip modified slide hammer isn't going to do much for me, but I've got to try.

If it fails, the heads aren't anything special, so not a big deal. I'll purchase the aluminum heads I've found on FleeBay and be done with it. I think buying them will be cheaper than having a bunch of machine work done to poor heads, can come out ahead on the flow and performance anyway.

I've got a plan and I'm sticking to it, lol

@Pᴀᴜʟsᴛᴇʀ2 I might as well throw the idea up here since I spent so much time crafting the fine drawing above :)

It involves a little bit of metal fabrication if that makes you feel better :D

Just honk down on the box section a quarter turn at a time, alternating between the two shafts to keep it nice and level

I hope you can see the image. Please don't tell me you're at work now :/

@Zaid - I'm at work, but some recent changes in the way the firewall works allows me to see the image ... though their round of changes totally screws other things up (like right clicking to copy a link or telling the browser to pop up a new tab from a link ... argh ... very frustrating).

How does the box section connect to the broken valve?

I would drill a hole into the bottom face to keep it from slipping. The top face can do the pressing then

Not to be a naysayer, but the way it's stuck, I'd bet the box section would do nothing but bend.

Well then in that case you're really stuck

Well, if the slide hammer doesn't work, you're exactly right.

If mechanical advantage won't help you, the valve's as good as fused

I just hope there's enough mass to the slide portion of it to actually do something.

I guess it depends on how it's rusted

Your valve. Your call

Yup. It's stuck in there pretty good, no doubt. If I am able to get it out using the slide, I don't damage the guide in the process.

The valve is already broke/stuck ... if it breaks something worse, it was broke to begin with.