Do you have to take head to machine shop while replacing valves?

[m3BMW95]

I mis shifted two nights ago, and I have been working on taking my head off. It is getting close, just waiting on the specail tools. I want to do this right, but as cheaply as possible. When I see head gasket DIY, everyone always mentions taking their head to a machine shop. Would I be alright just replacing the valves, and putting it back on? And my compression in every cylinder was 185 psi except No. 6 was 0. Is there still a chance the valves in the first five cylinders could also be bent, it just isn't showing up in the compression test? Thanks, and I hope to have her running again by next weekend!

[John in Houston]

You'd be best served taking it to a machine shop and having them check it out unless you are quite competent in head work. Here are some things to look out for:

If you bent a valve you may also have damaged a valve guide... and those have to be pressed in and out.

You may also have some damage to the valve seat which would then need to be blended to allow the valve to completely seal against the head.

You will also need a tool to compress the valve springs to remove the locks... and then to compress the spring to reinstall the locks... all while not damaging the face of the valve.

Overall, it can be done... but it is alot of work and if you don't do it right... you'll be doing it again.