A Quick WUR Adjusting Question

[Tidybuoy]

I've posted a few CIS questions and have gotten my car running near perfect - Thanks to all the great advice!

Since I have acquired a few WUR's, I built a #033 wur and got my warm and cold pressures near perfect and the car is running well.

I also had enough parts to put together another #033 wur so I did this and swapped it onto my car and got the pressures the exact same as the earlier wur - this time the car runs different and jerks a bit.

I took it apart and checked everything including the oms on the bi-metal strip, the wur holds vacuum, etc..

Next, I swapped a wur rebuild kit that I had acquired and I noticed that the diaphragm looks different and noticed that the small perch for the small spring screws in and has an Allen adjuster on the other end. This got me thinking that this piece of the diaphragm has an adjustment - But, I do not know how this should be set.

When setting my warm pressures, I first tapped out the bi-metallic spring "plug" out far enough that I would only be testing the warm side. I would tap in the plug later to set the cold pressure but do the warm side first without any interference from this part. I had also previously taped out the warm side barrel so that I would be starting from a decent point and then adjust as needed. Lastly, got the wur warmed up, engine fully warm, connected vacuum gauge and pumped up to 52 mgxx (cant remember exact name for it) and then tapped in the barrel till pressure was at 3.6bar with vacuum connected.

My quick question: should I be adjusting the small spring perch till the warm pressure (without vacuum applied) is to a certain point?

Thanks for any additional advice.

[T77911S]

this is what i have conluded on the allen adjustment, no testing to confirm other than checking AFR's.

the vacuum control is for WOT enrichment. as your RPM's increase towards WOT, the vacuum will start to go down. there is a point where the vacuum will no longer hold the diaphragm up keeping the CP hi. it is this point that i think the allen is adjusted for.

with a hand vac and gauges conntected you could test a find out what that point is. BUT, you would have to know what the vacuum is at the RPM you would want the mixture to go richer.

the AFM bowl is also shaped to go richer in the upper RPM's. when i did my testing, i was seeing the mixture start to richen up at around 4k RPM.

[Tidybuoy]

I somewhat understand your response but am still a little confused.

Jim's CIS Primer Page shows a warm pressure spec of: 3.2 @40 and 3.6 @40 with Vacuum. I was thinking that tapping in or out the large warm pressure barrel (the section the fuel connects to), only adjusts one of the two specifications - I think the latter with the vacuum port pumped to 52 $#@% something, and then adjust to the 3.6.

Now with the vacuum not connected, I need to be at 3.2 and maybe the allen screw adjusts for this.

My interest was peaked when I took two identical wurs and adjusted both to WP 3.6 with Vac but one causes the car to run bad and the other runs good. I haven't had time to compare the lower numbers for each wur but the weekend is just a few days away.

[T77911S]

no, not correct.
the metal part on the diaphragm can only move so far and that is based on the "seat" that it rests against when vacuum is removed. that allows for a .8bar change in pressure. the ONLY way to change that .8bar is if you could move the seat that is on the (i think) middle section.
(i am doinf this from memory of how it comes apart). the brain leask mod to the 930 WUR does this. he makes it so you can move that seat which changes boost pressure.
the allen ONLY changes the pressure on the smaller spring. that spring is trying to push the diaphragm down, vacuum is pulling it up. which ever one is stronger, wins.
adjust the allen so there is less compression on the spring and it will take higher RPM's before the CP goes rich.

not sure about the spec of your car, but that WUR is set up for a .8 bar change. you should have 3.6 with vac and 2.8 without.

make sure the cold pressure adjustment is not effecting warm pressure.

i would not mess with the allen or the seat in the middle section.

[Tidybuoy]

Originally Posted by T77911S

make sure the cold pressure adjustment is not effecting warm pressure.

i would not mess with the allen or the seat in the middle section.

Just to clarify:

1) I know that cold pressure is not affecting warm because I set the warm first and to do this, I have the cold pressure "plug" moved up enough that the bi-metallic spring is never touching the round springs. Once I have the warm pressure right, I will tap in the "plug", when cold, to set the cold pressure to spec.

2) I am forced to mess with the allen because rebuild kit had the diaphragm/gasket without this seat for the small spring. It was just a threaded hole. I thought it was the wrong part until I noticed that it was threaded and requires removal of this seat from the old part and transfer to the new. So the question is, how far does that thing get screwed in - basically, it's adjustable and needs to be adjusted to the correct setting.

3) Lastly, all of this is for my "spare" wur. My original wur is working correctly and now I am attempting to recreate my success on a second wur that I have.