Is it warming up too rich when the WRD has this behavior?

[rgafitanu@gmail.com]

Hello,
I read all the posts regarding the WRD and I believe I learned a lot in understanding how it works. However I still need some help.
I start the car, the CSV gives the squirt to get it running then:
- Stage 1. The rpm hovers below 1000 rpm  with tendencies to drop to 500 rpm for about 5 to 10 seconds. I usually push the accelerator a couple of times and avoid this drop.
- Stage 2. The rpm goes to about 1200 rpm and there is a strong vacuum at the WRD. It lasts maybe a minute.
- Stage 3. Around 140F (on the instrument pane gauge) the rpm starts to drop. There is still vacuum.
- Stage 4. After about 30 seconds the rpm goes around 500 rpm, "chasing" with tendencies to drop further but it never stalls. There is little vacuum left and split linkage test increases the rpm about 200 rpm with a 1/8" push on the throttle linkage. At this point I usually drive away and everything is OK. If I don't drive away:
- Stage 5. The vacuum is completely gone but the rpm is still around 500 rpm for about a minute or two.
- Stage 6. The rpm recovers slowly to 700-800 rpm.
After driving for a while the rpm goes higher to 900 rpm.

From what I read so far I think I have a rich warming condition or there is a considerable lag between the closing of the air slide and the end of the IP pin travel. I imagine that the heat feeler continues to go down after the air is closed. While closing the air the mixture becomes too rich and the rpm drops in Stages 4 and 5. The heat feeler continues to extend leaning the mixture and bringing it to correct ratio, thus the rpm goes back up in Stage 6. This may also explain higher idle after driving and engine up to operating temperature.
Am I correct in assuming this rich condition or lag between the air closing and fuel leaning?
I still have no explanation for Stage 1.
Should I start to play with the oval shims and/or pin adjusting nuts to see which way it changes?
one thing I should verify, vacuum at the WRD after driving at 900 rpm idle to see if the air slide did not overshoot.

Thank you,
Radu

[Tyler S]

You are correct in that you may not have enough air to fuel during these "stages". If your split linkage test shows a rich condition across the board during warmup, then first try and adjust pin length making it shorter. You may also need to remove an equivelant size oval shim. Keep track of your adjustments.

[ja17]

Pin length in the WRD, is set to make sure that the extra cold idle air is closed off at the correct temperature. This is "ground zero" for the WRD adjustment. The oval shims adjust mixture during warm-up. The barometric compensator has round shims which can adjust the fuel injection at all speed ranges and temperatures. The more difficult "rack adjustment" also adjusts the injection at all speed ranges and temperatures. The large slotted screw on the intake, adjust idle air (all temperatures) but mostly used for warm engine idle. The thumb screw on the back of the injection pump adjust fuel mixture up to about 1,500 rpms (all temps), two dark color screws inside the injection pump (rear governor springs)  adjust mid-range (1500-3500 rpms) all temps, and two light colored screws inside the injection pump (rear governor springs) adjust high range(above 3500 rpms) all temps.

 Before making injection pump settings check make sure your engine is in good tune. Make sure your engine linkages are correct, your ignition timing is correct, your distributor is working properly (vacuum retard, advance etc), and the  fuel pressure and volume is correct. The barometric compensator on the IP,  and the "heat feeler" in the WRD can also be defective. When the baro compensator goes bad, the injection usually goes lean. The WRD "heat feeler" can be measured or tested to make sure the cold engine idle air operates and closes off when it should.

Start by checking all tuning items and make sure the cold engine idle air closes off when it should. Next determine and adjust the fuel mixture on a warmed up engine all speed ranges. Normally a rack adjustment or baro compensator shim adjustment, idle mixture thumb screw adjustment or intake air screw will be sufficient. Internal adjustment of the pairs of governor screws is a fine tweek, but not normally needed. Lastly adjust the WRD for cold running. Add or remove oval shims to adjust fuel mixture during warm up period. Changing pin length will also alter the fuel mixture during warm-up, however you may wrongly change the shut-off temperature of the cold engine idle air.

There is a compound shaped cam inside the injection pump governor unit which develops wear grooves over time. This cam moves the rack depending on engine rpm. If the cam is badly worn, all these injection pump adjustments can compensate to an extent, but may not be able to solve every issue perfectly. .

[Jowe]

Joe,
This was so splendid described so I copied it into the Technical Manual under fuel injection pump section.

[ja17]

Thanks Jowe !