Quote Originally Posted by Dash01 View Post
I'm stopping ~1" out because at that point the bolts really get stiff, and I don't want to force them for fear of buggering the threads machined into the block.

So, rather than taking the chance of messing up the threads, I thought I'd ask advice from others more knowledgeable.

I've removed the head on an M30 a couple of times, but never had this sort of difficulty--normally the bolts just loosen to easily remove by finger after a turn or so with the wrench. Not these, though. What could be fouling them? I squirted some penetrating oil down each bolt shaft, so we'll see if that helped overnight.

This is a replacement engine from a wreck, so I don't know its history. Any chance such engine could be so warped as to foul the middle headbolts?
The first M30 I played with did this - I have no idea what caused it, though I suspect it was oil on the threads creating an airlock/etc. Wind them back in and out several times - see if you can get them to loosen up? The one I had I just got a bigger bar to wind them out, no damage just very clean threads.

There's always the possiblity that they've been stretched and the threads are a bit shot on them