I don't want the engine mount in place when I start putting things on the firewall, but while I'm waiting for that stuff to arrive, I figured I may as well get it fitted. The bolt attachment points come with small holes pre-drilled, and the top steel brackets on the cockpit side of the firewall have the same size holes drilled. Those are the only matching holes of the 6 required. I put temporary bolts in the top to see what the rest of the mount looked like.
Well, it turns out I have a common issue. This is a pretty big weldment, so it's not uncommon that no matter how good things look in the jig during welding, once the mount is removed it has a mind of its own. When my top mounts are flush and the lower middle mounts set against the firewall, the two lower outside attachment points don't set flush. I pulled the mount off and put a level across it to make sure it was the mount and not my firewall that was uneven. Yep. One side is about 1/16" off and the other side is 1/8" off. I emailed Van's to see what they say, but I think the answer is just going to be to make some shims to fit the gaps. I went ahead and ordered some 1/8" thick stainless steel bar, assuming I'll need to make shims. This is the second time in a week that a lathe/mill would have come in handy!
Even though I can't finish the fitting until I have the shims made, I went ahead and drilled the top two holes to 3/8". Regular drill bits worked, but I think I'd rather finish the final dimension with a reamer. The drill bits kept catching as they went through the multiple different layers of material. Since I have to wait for the steel bar anyway, I ordered a 3/8" reamer as well. It still blows my mind that this is all that is required to support 250+ lbs of engine.
