Factory Dual Solex PDSIT Carburetor Adjustments

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DannyZ
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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by DannyZ » Wed Mar 13, 2019 6:33 pm

Latest post of the previous page:

Wow, thanks for the quick feedback.
a) do you have too fast of an idle speed (recommended at 1,050 rpm max
Not anymore. Used to, but after my first round of adjustments it idles right around 1,050 rpm consistently once warm.

For STEP 1: Set Throttle Stop Screws (Diagram 1 #5)
Stop screw adjustments are purely mechanical and are not affected by the retard nipple...

Gotcha, that makes total sense.
DannyZ wrote: ↑Tue Mar 12, 2019 10:43 pm
For STEP 4: Synchronize carburetor mixtures
a) Should I unblock my retard intake on the left carb again during this step?
Not necessary. By "retard intake" (??) do you mean the vacuum nipple ? If you did have a leak-free retard diaphragm in good condition on your distributor, there would be no air flow at all, it is just vacuum. So, it would be exactly the same to the carburetor if you had the nipple blocked off or going to a healthy vacuum unit.
Yes, by vacuum intake I meant the vacuum nipple. And got it, that makes sense.

DannyZ wrote: ↑Tue Mar 12, 2019 10:43 pm
b) My “Mixture Reference hose” on the right booster elbow plugs directly into the intake on my right carb
I do not hear any hissing OR get any changes in RPM with the finger ON/OFF tests
What "intake" are you referring to? If you have that hose coming from the right brake booster elbow to the EGR nipple on the carburetor, it is an air leak, it is breathing air from the right carburetor and that is screwing everything up. The "mixture reference" is coming from the brake booster nipple end. That is where the vacuum originates.
Sorry for not clarifying this better. The intake I am referring to is the EGR nipple, NOT THE BRAKE BOOSTER (Since mine is a 74 my brake booster does not have a nipple on it. Please see my photo for better clarification of my set up:
Image
For STEP 5: Set Central Idling Speed/Mixture
c) Should I still pull my Mixture Reference Hose (step 5b) from the right carb? When I do remove the hose and put a finger on the end the idle DOES NOT go down, or change for that matter.
You have to fix this. The hose comes from the right brake booster elbow nipple, and it must either go to a functioning thermostatic valve in the right air horn, or be blocked off. Do you have a functioning thermostatic valve in the right air horn? Do you have another hose going from that valve to the air cleaner preheater valve nipple? It cannot allowed to breathe. Seriously, engine damage (#1 intake valve recession or a burned exhaust valve, for example) is right around the corner for you if you do not address this oversight.[/quote]

Again, I apologize for not clarifying this better. I hope my photo helps to explain. I do have a functioning thermostatic valve in the right air horn (ie brake booster elbow???). And I do have another hose going from one of those two valves to the air cleaner preheater valve nipple. So am I ok and not in serious danger?
let us know if there is a good hiss coming from the central idling circuit air intake (take off the little central idling circuit air intake pipe/elbow from the left carburetor central idling circuit brass air intake.
Yes, I have a great little hissing coming from the central idling circuit air intake.

I hope all this helps to better explain my set up. Does it sound ok despite using a distributor without a vacuum retard(If I hadn't just got it I would be much more inclined to replace it)? Or am I just showing you more problems...
If all of the above issues are ok, any suggestions for:

Q#1: synchronizing my carburetor mixtures (step#4) since I am not able to perform the Mixture reference hose "ON/OFF" test with my set up (I do have an EMPI synchronizer gauge that has made a huge difference)?

Q#2: how to get the central idle mixture screw set just right since my set up doesn't allow for "finger ON/Off" the mixture reference hose as detailed in step#5b.

Slowly but surely these carbs are making more and more sense. I remember asking a vw mechanic a while back if he would adjust my carbs and he just laughed at me and told me to replace them. I'm glad I didn't do it. Again, thanks for everything.
Attachments
Right-Carb.jpg
1974 Westfalia

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Amskeptic
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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by Amskeptic » Thu Mar 14, 2019 6:51 am

DannyZ wrote:
Wed Mar 13, 2019 6:33 pm
Wow, thanks for the quick feedback.
Danny, I was all stuck on the 1972 dual carbs with that one-year-only vacuum source off the right brake booster elbow.

You, however, remain stuck in vacuum hose limbo.

Do you know where the correct vacuum source nipple for the preheater thermostatic valve resides?
Diagram 2 shows it for the 1973-74 engines. It is on the central idling plumbing under the air filter, it is a little vacuum nipple next to the big pipe (blocked off) that used to go to the air pump.
Is it capped? Is it welded shut? Is it just open and sucking in air god forbid?
It is your vacuum source so you can do the mixture reference test!

I need to know how this missed your attention so I can redo the write-up and diagram.

The nipple off the right carb only has a little vacuum at mid-throttle for the now blocked-off EGR valves! thus, the nipple needs to be blocked off!)
Colin
BobD - 1978 Bus . . . . . . . . . . .111,155 miles
Chloe - 1970 bus . . . . . . . . . . . 206,820 miles
Naranja - 1977 Westfalia . . . . . 98,380 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 78,885 miles

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DannyZ
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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by DannyZ » Fri Mar 15, 2019 10:27 pm

Hopefully this can help clear up the vacuum hose limbo:
Yes, I know the correct vacuum source nipple for the preheater thermostatic valve and it is hooked up.
On my Central Idling circuit my vacuum nipple for where the mixture reference hose is supposed to connect is blocked off and welded shut (as is the big pipe right next to it that used to go to the air pump). Please see my pic and markings on your diagram to help illustrate this. Image
Image

So I am guessing that I am out of luck in this regard for using the central idling circuit to perform my mixture reference test? Any other ideas for:

Q#1: synchronizing my carburetor mixtures (step#4) since I am not able to perform the Mixture reference hose "ON/OFF" test with my set up (I do have an EMPI synchronizer gauge that has made a huge difference)?

Q#2: how to get the central idle mixture screw set just right since my set up doesn't allow for "finger ON/Off" the mixture reference hose as detailed in step#5b.

It makes good sense in your write up. It didn't miss my attention, I just didn't clarify my specific set up clearly enough. Again, sorry for that.
And I will block off the nipple off the right carb that was part of the EGR stuff. Should I also plug the other end of the mixture reference hose that goes into the bottom of the right booster elbow?
Attachments
InkedDualCarbDiagram2 -with my set up_LI.jpg
Central-Idling-circuit-plug.jpg
1974 Westfalia

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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by Amskeptic » Sat Mar 16, 2019 5:02 pm

DannyZ wrote:
Fri Mar 15, 2019 10:27 pm

So I am guessing that I am out of luck in this regard for using the central idling circuit to perform my mixture reference test? Any other ideas for:

Q#1: synchronizing my carburetor mixtures (step#4) since I am not able to perform the Mixture reference hose "ON/OFF" test with my set up (I do have an EMPI synchronizer gauge that has made a huge difference)?

Q#2: how to get the central idle mixture screw set just right since my set up doesn't allow for "finger ON/Off" the mixture reference hose as detailed in step#5b.

If you decide not to hook up the thermostatic preheater valve to a vacuum source, you lose engineering that is friggen critical for good driveability.
I saw the photograph of your central idling plumbing, and I think you can just saw/dremel off that stupid weld job on the vacuum nipple so you can have a correctly functioning valve and preheater, AND do the mixture test.
Saw off the tip of the nipple. You only need 3/8" nipple remaining to clamp on the vacuum hose with. You can even drill out the thing if weld is still visible inside at the 3/8" mark. If you need to drill, you will need to remove the entire central idling plumbing, and I know you will too, because you care about a proper job and do not want drilling swarf in the intake passages! I just know it.
Colin
BobD - 1978 Bus . . . . . . . . . . .111,155 miles
Chloe - 1970 bus . . . . . . . . . . . 206,820 miles
Naranja - 1977 Westfalia . . . . . 98,380 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 78,885 miles

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DannyZ
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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by DannyZ » Sun Mar 17, 2019 11:18 am

Awesome. All this makes sense. I will let you know how it all goes. Thanks again for everything here and your patience!
1974 Westfalia

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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by Amskeptic » Fri Mar 22, 2019 10:04 am

DannyZ wrote:
Sun Mar 17, 2019 11:18 am
Awesome. All this makes sense. I will let you know how it all goes. Thanks again for everything here and your patience!
I'll wait here .. . . . .
Colin
BobD - 1978 Bus . . . . . . . . . . .111,155 miles
Chloe - 1970 bus . . . . . . . . . . . 206,820 miles
Naranja - 1977 Westfalia . . . . . 98,380 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 78,885 miles

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DannyZ
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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by DannyZ » Mon Apr 08, 2019 12:27 am

Just wanted to give a quick update. I was able to remove the weld and re-install the mixture reference hose where it needs to go. Makes every step now possible.
Everything is making more and more sense each time I work on these carbs. Thanks so much for everything.

Just for clarification, are the air horns still off for steps 4 and 5: Synchronize carburetor mixtures and Set Central Idling Speed/Mixture?

Thanks again for your patience and explanations!

[image][/image]
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1974 Westfalia

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xyzzy
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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by xyzzy » Mon Apr 15, 2019 4:06 pm

Also aren't your hoses on the right air-horn reversed? On my 73 (and in Colin's diagram), looking at the fully assembled air-cleaner and the right air-horn, the mixture reference hose should be on the *left* and the thermostatic valve hose on the *right*....

Image

Those are reversed....no?
---
1973 Westfalia
Encinitas, California USA

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DannyZ
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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by DannyZ » Wed Apr 17, 2019 3:30 pm

Yes, these hoses were reversed. Now that I reconnected the mixture reference hose in the proper place, I have switched these hoses as well.
1974 Westfalia

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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by Amskeptic » Wed Apr 17, 2019 7:45 pm

DannyZ wrote:
Wed Apr 17, 2019 3:30 pm
Yes, these hoses were reversed. Now that I reconnected the mixture reference hose in the proper place, I have switched these hoses as well.

Adjust mixtures with the air horns on!
Colin
BobD - 1978 Bus . . . . . . . . . . .111,155 miles
Chloe - 1970 bus . . . . . . . . . . . 206,820 miles
Naranja - 1977 Westfalia . . . . . 98,380 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 78,885 miles

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DannyZ
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Re: Factory Dual Solex PDSIT Carburetor Adjustments

Post by DannyZ » Wed Apr 17, 2019 7:55 pm

Perfect! Thank you for clarifying that Colin. I figured but just wanted to double check.
1974 Westfalia

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