Old Race 340 Teardown

Super Sleeper said

Thanks, that's an easy measurement to make although I don't have a square that is that large I can certainly get one! My question is from complete ignorance, but also because when I measured the distance between the banks at the top of the China wall I got a measurement that would seem to indicate that quite a bit of material had been removed. So angle milling is done to get the valve angle right?
On the lifter bank angle, I'm pretty sure mine is the stock 59 degrees because the pushrods come pretty close to the block at the deck. Some reliefs have been ground there. I can't speak for all X-blocks.

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Angle milling is done to decrease chamber volume quicker than a flat mill and to change the valve angle a bit. It also raises the port slightly. It’s a lot of work because you have to spot face the bolt bosses, although I’ve seen several times where it wasn’t done, or was done halfassed and it makes a mess. When you mill enough off the heads, either by angle milling or flat milling you need to machine the China wall to make sure the manifold doesn’t hit the China wall. You can machine the intake manifold but when you take a bunch off the heads and then deck the block to get the piston out of the hole the .060 you said yours are, there isn’t enough materiel to machine off the intake. So you machine the China wall.