Slow but sure.
POSTSCRIPT --- NEW YEARS 2012:
Many builders cruise the VAF archives looking for ideas and how others did things. It's only fair to report back after lots of flight hours with news of how well something worked.
The above method of attaching the plenum lid needed modification. Problems in two places; first the forward ends of the aluminum side flanges for plenum lid attachment kept cracking at the 1/4" cylinder head attach screws. Second, the curved flange spanning the center between the intakes also cracked. The plenum applies a considerable air load (over 100 lbs per sq foot at high speed) to the attach flanges and it is concentrated at the span across the inlets.
So, a revision. The plenum lid got a flange between the inlets and additional material on each side above cylinders 1 and 2. Only a small part of the curved center flange remains. The major fastening in that area is now #10 screws in shear. The lid now attaches at cyls 1 and 2 using the 1/4" screws, with a clamp plate so the glass doesn't bow outward and leak in the span between them. Most of the aluminum flange in that area has been removed. I'll fly another 150 hours and see how it works.

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