Problem solved (if anyone is interested)
I had hooked up a spare tach for testing as I went out for the mileage test. Just tossed it on the seat. This morning when I started it, It said the idle was high, but it wasn't.
The cylinder selector switch had gotten bumped into the 4 cyl mode.
So the "3500" was probably 2700 or so.will recheck it and am pretty sure it will be much closer to the odometer error.
That makes sense. 46 mph at 3500 rpm would definitely have seemed a little slower than expected!
Also, for the rear end gears I was just assuming you have the same 6.40/8.72:1 ratios as me. Have you confirmed this? And all tests are being done in the high gear?
