I resurfaced my E82 heads following the method discussed here. It took days and hours per day to accomplish.
One of the exhaust valve guides was out of place in each head and after trying to press one back into place myself and cracking the guide, I took it to a shop to have those two replaced. They inform me that there are cracks between the valves and that they all have to be ground out and welded, and then the heads would have to be resurfaced since the heat op the welding would warp the heads.
After reading up on head cracks on this forum I could see that the cracks went in pretty far so I went to the junk yard and procured two heads with only the beginning of one crack.
Now I am resurfacing the heads again and many hours into the process. I start with 150 grit sandpaper and even put about 5 pounds of weight on the head to increase the pressure and it goes soooo slow.
I see from the original thread that people were doing a head in just minutes. What the heck am I doing wrong?
Also how much of the fire ring needs to be removed? That is the last thing to go and it takes forever.
Lastly what else sould I look for on these heads? I never heard of the crack thing until the shop pointed it out (and they didn't look like cracks, they looked like a casting seam or something). Is there something else that I should look for that might render the head bad?