Update: I put a couple of brass fittings in the hose that connects to the duct over the cam cover. The hole that air draws through is now about 1/8-inch (~3 mm) in diameter, compared to the hose fittings which are about 1/2-inch (~12 mm). The idle is a little higher in neutral (~900 RPM) than it was and drops to ~800 RPM when I put it in Drive. I'll check it with the air conditioner compressor engaged tomorrow. It definitely idles smoother than it used to, probably because now the idle mixture is a little richer than it was. These engines desperately need balance shafts; they will never be smooth at idle without them.

Next tests are highway performance, drivability, coast down, cold start, and fuel consumption.

I think we're on to something here, guys.

Don, y'all
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