033 WUR Questions

[1150ss]

Hi everyone,

Need some help from the CIS experts out there. Trying to adjust base and zero vacuum pressures on a 033 WUR. The two adjustments that I know of are adjusting the rod length inside the WUR, which from what I am told sets baseline fuel pressure. And changing the height of brass bushing which in turn adjusts fuel pressure at zero vacuum by changing the height of the seat for the fuel pressure diaphragm.

I assume by shortening the length of the rod you would lower the baseline fuel pressure. And by lowering the fuel pressure diaphragm seat you will lower the fuel pressure at zero vacuum. However I am finding there is a correlation between the two that I can't figure out.

Ultimately what I am trying to do is correct a very lean condition at light throttle on my 2.7 with SC cams.

Anyone out there can steer me in the right direction?

Thanks!

Scott

[T77911S]

that wont do it.

how lean is it?
what RPM is this happening

changing the CP effects the mixture across the RPM range. also, once you change the CP, you will just correct the mixture back to where it was with the mixture screw.

if you start screwing with the allen on the bottom of the WUR that basically changes the RPM at which the mixture goes rich based on the amount of vacuum needed to keep the diaphragm pulled up. I have not looked at an 033 in a long time. if the diaphragm rests on a plug on the bottom of the WUR and that plug can be moved up or down then yes, you could change the amount the CP changes when it goes rich,. BUT, this ONLY effects WOT. the CP change when vacuum is removed should be around .8bar.
if you shorten the rod inside the WUR then you are REALLY screwed because you cant go back,

my advise and I STRONGLY suggest this, not often I say that, DO NOT screw around with this the way you are trying to do it.

if you really want to change the CP, the way to do that is to raise or lower the "plunger" that the fuel lines attach to. there is a mod to make it adjustable so you can raise or lower it. BUT, you can take it apart, raise the plunger (lowering the CP), put it back together then knock it down to set the CP to where you want it. the problem is if you go too far you have to take it part and start all over.
then you will have to go back and set the cold CP. that is set with the smaller pin. you raise or lower that, again, you have to take it part if you knock it down too far. not to mention you have to raise this pin FIRST to set the WCP so it does not effect the WCP setting.
this still wont fix your problem.

if you have a lean condition first verify you don't have air leaks
check and verify timing is working correctly and set correctly.
richen the mixture if needed, if it will run ok.
check injectors/fuel flow
check system pressure. I would probably do testing and lower (corrected) system pressure and/or raise CP.

[boyt911sc]

Originally Posted by 1150ss

Hi everyone,

Need some help from the CIS experts out there. Trying to adjust base and zero vacuum pressures on a 033 WUR. The two adjustments that I know of are adjusting the rod length inside the WUR, which from what I am told sets baseline fuel pressure. And changing the height of brass bushing which in turn adjusts fuel pressure at zero vacuum by changing the height of the seat for the fuel pressure diaphragm.

I assume by shortening the length of the rod you would lower the baseline fuel pressure. And by lowering the fuel pressure diaphragm seat you will lower the fuel pressure at zero vacuum. However I am finding there is a correlation between the two that I can't figure out.

Ultimately what I am trying to do is correct a very lean condition at light throttle on my 2.7 with SC cams.

Anyone out there can steer me in the right direction?

Thanks!

Scott

Scott,

I re-read your above post more than a dozen times and still could not understand what you are trying to do. Have you successfully rebuilt a WUR-033 before? If not, this is your chance to do it. Use a pressure gauge to measure the cold control fuel pressures versus time and take note of the ambient temp. when the test was done. This would be your base line data. From the initial CCP (cold control pressure) it would slowly and gradually increase to get to WCP (warm control pressure). Next, apply 15" Hg vacuum and record this reading.

BTW, the advise about altering the pin length to set the base fuel pressure is not the right way to do your calibration. While it is true that it has a direct effect on the pressure reading for CCP, the effect would be a disaster for the WCP. Second, what about the 'brass bushing'? What brass bushing were you referring to? I am not aware of this part. Could you post a picture of your WUR? Thanks.

Tony

[ossiblue]

Let's put the most important parts of both posts, together for you. I suggest you go in the following order:

1) my advise and I STRONGLY suggest this, not often I say that, DO NOT screw around with this the way you are trying to do it.


2) if you have a lean condition first verify you don't have air leaks.

3) check and verify timing is working correctly and set correctly.

4) Use a pressure gauge to measure the cold control fuel pressures versus time and take note of the ambient temp. when the test was done. This would be your base line data. From the initial CCP (cold control pressure) it would slowly and gradually increase to get to WCP (warm control pressure). Next, apply 15" Hg vacuum and record this reading.

Once you have completed the above steps, report your findings. Moving on to any adjustments or further tests, will depend on your results.

Your feedback is essential.

[T77911S]

the pin he is referring to is the 3mm allen on the bottom.

I suggested timing.
he is running a 74 2.7 dist with SC cams. the spec for the 2.7 is 35 degrees. suggested retarding it and give it a try.
he also thinks the vac advance is connected BELOW the throttle plate. that would give advance at idle and none above that if it is a vacuum retard port.

he is running rich at idle and around 15 at cruise, the it goes leaner with light throttle.
he has been through everthing else
rebuilt FD, WUR,Dist, injectors. sealed the intake, IJ sleeves, air box.

[T77911S]

this is not your WUR, the top is the same as far as making it adjustable or adjusting it.