[PeteKz]

WUR 089: SP= 4.8bar (70 psi)
CCP at 65F=2.0bar (30psi),
WCP without vacuum =3.7bar (54psi), with vacuum=4.2bar (62psi). This is above the spec.

WUR 033:
CCP at 60F=1.8bar (26psi)
WCP without vacuum =3.5bar (52psi), with vacuum =4.2bar (62psi). This is above the spec.

Although I measured the WCP as the same for both WURs, the 033 caused the engine to run one full AFR point leaner at all conditions, showing AFRs in the mid 15 range at cruise at from 60-80MPH, and the low 14 range at idle. See my post above for the AFRs on the 089. Both WURs displayed the same behavior during acceleration and deceleration, that is, the mixture initially went lean during acceleration (high 15 to 16 range), then dropped about 1 to 1.5 AFR point to a richer AFR (in the mid 14 range). And when I took my foot off the gas pedal, the opposite happened: First the AFR went rich, then leaned back to the upper 15 to upper 16 range. As noted above, this is intuitively opposite to what I expect and want.

I did not change the CO screw between changing the WURs, so I would expect that if the WURs have the same warm control pressure, that the AFRs should be the same. But as noted, they were not.

I noticed a very curious measurement when testing with and without vacuum. With a vacuum of only 0.1bar, the WCP went up about 12 psi, but as I increased vacuum to the Bosch specified measuring value of about 0.5 bar, WCP dropped back 2psi. That is, with the higher vacuum applied, the CP reduced a little! That is the opposite behavior of what I expect (more vacuum should push harder against the pressure regulator in the WUR and cause higher CP), so I checked it several times to be sure. Strange.

I'm also contemplating whether the M1 cam I have in my engine is sufficiently different than the SC cam that it affects WUR behavior. I may have to hook up a manifold pressure gauge in the cabin to see what that does as I accelerate and decelerate.