There has been some discussion offline about this subject, so rather than answering multiple messages I thought I'd just post my comments here for all to see...
Sonex strongly recommends that builders assemble the engine strictly in accordance with the AeroVee Assembly Manual. Any deviation from that makes it hard to diagnose problems that may be introduced by individual builders doing things different ways. Once a builder deviates from the manual in one place, it becomes easier to deviate in other places. Sort of like that snowball rolling down the hill. At any rate, Sonex cannot and does not "approve" anything that is not detailed in the manual. Local "experts" may have a "better idea", but if it's not in the manual, you're on your own.
Regarding the case half bolts: There is NO specific torquing sequence for the perimeter bolts. Only the 6 large main bearing nuts have a toque sequence. The builder is free to tighten the case perimeter nuts and bolts in any pattern he or she wishes.
Regarding my comment on a "torque extender" for torquing cylinder heads. As many of you know, when checking torque on the AeroVee heads, you have to remove the rocker arm shaft. This is fine since you are no doubt going to adjust the valve clearance anyway. But two of the nuts on the top of the head are hidden by the intake elbow. Common practice is to remove the intake elbow to get at those two nuts. This introduces a possible issue with induction system leaks if you don't get the elbows resealed to the heads properly.
Why mess with something if you don't have to! Rather make yourself a toque extender out of a spare 15 mm open end wrench. You'll need the wrench, a spare socket that fits your 3/8 drive torque wrench, and a welder. (The socket can be any size, but something that is about the same width as the wrench works very well.) Measure 4 inches from the center of the wrench's open end and mark the handle of the wrench. Then weld the socket on the wrench so that the center of the 3/8 drive is right over the 4" mark. You now have a 4" extender for your torque wrench. Now all you have to do is calculate the extra leverage of the 4" extension and set your torque wrench accordingly. You'll need to know the length of the handle of your torque wrench in order to do the calculation.
Let's say your torque wrench is 12 inches long from the center of the square drive to the center of the handle. With the 4" extension installed straight out you'll now have an effective length of 16 inches. The formula is as follows: Torque wrench setting (M1) equals desired torque (M2) multiplied by the basic length of the wrench (L1) divided by the extended length of the wrench (L2). So the formula is M1 = M2xL1/L2.
Plugging our numbers in, the formula looks like this M1 = 18x12/16. 12/16 = .75. 18x.75 is 13.5. So you would set your torque wrench at 13.5 lb-ft in order to achieve 18 lb-ft on the nut. Now you can slide your extension down between the intake elbow and the head and torque those two nuts without having to pull the elbow off.
Now, if you put the extension at a 90 degree angle to the torque wrench, you haven't actually extended the length so you can leave the setting at 18 lb-ft. But I've always found that to be awkward, so I just use the extension straight and change the wrench setting. Either way, it saves messing with the induction system, which is a good thing in my book.
Now that you've endured all that, you can just go to
http://www.rv7.us/a_u-torquewrenchsetting.htm and plug in the numbers and you'll get the answer!
Hope this helps!!