Solex 32 PHN-2 oddity

[Komissar]

Hello,

I was fiddling around with a friend's Solex 32 PHN-2 carb that was bought NOS to be installed on a 1500 engine.
Even though the carb was NOS we cleaned it a bit, by opening the top cover, plus all the threaded plugs we could unscrew from outside (including the main jet carrier), submerging the carb in gasoline and blowing in all the orifices we could find with compressed air.
We did not open the accelerator pump assembly since we did not to mess around with the needle valve and the check ball.

After that, we reassembled the carb and installed it in the car. We found out that the engine starts and works at medium to full throttle but it dies at idle. This happens (sometimes) even with the choke on.

After we checked for vacuum leaks using a can of brake cleaner (and found none) we started looking for faults with the carb.

After a couple of days we think we have identified the problem, and it's an odd one, and therefore we seek advice.

While playing around with different idle jets (we suspected from the beginning that an idle jet is to blame) by accident we found out that if we unscrew the idle jet quite a lot the carb starts to work fine, keeps the idle speed when warmed up and responds to idle and mixture screw adjustments.
When reading the Solex 32 PHN manual listed here on the Samba we found out that under the small cover on top of the carb there is an air hole that is supposed to mix the idle fuel with air.
From this page, third picture, the No. 3 item: http://www.thesamba.com/vw/archives/manuals/32phn/11.jpg
On our carb the hole is visible, however at closer examination we found out that is totally blocked by the casting of the carb itself, as a manufacturing defect.

Now, considering that the documentation on thesamba is for the Solex 32-PHN (the early model) and our carb is a 32 PHN-2 , and there might be slight differences between the two we decided to ask here on Thesamba before doing any irreversible modifications (like drilling that air hole).

So, is the Solex 32 PHN-2 supposed to have the No. 3 air opening, allowing air to mix with the idle fuel mixture, as seen in this picture http://www.thesamba.com/vw/archives/manuals/32phn/11.jpg ?

If so, can someone try to measure up the hole on their 32 PHN-2 carb and post the diameter here on this thread? It would help a lot.


Thanks in advance,
Laurentiu
_________________
1965 Sunroof Beetle
1972 Type 3 Squareback
1978 Skoda 105S

[EverettB]

I cannot answer your question about the PHN-2 but I do have a low mileage dealer replacement PHN-1 and it is drilled.

Unfortunately I don't have anything to measure the size of the hole, what would be the best way to do that if no one else can provide the information?
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[Komissar]

Hello EverettB,

Thanks for the reply. Regarding the measuring of the hole this is indeed a tricky problem. I would guess that the most precise way of doing it is using a precision conical feeler gauge, but I doubt many people have one at hand.
Another method would be finding something that fits in the hole (like a small drill bit, a piece of wire, and so on) - of course inserting the object in the hole without forcing it and than measuring the diameter of the object with a caliper.
_________________
1965 Sunroof Beetle
1972 Type 3 Squareback
1978 Skoda 105S

[raygreenwood]

[Komissar]

[Komissar]

Hello,


We are still struggling with understanding this odd carburetor.

Based on the charts found in this thread:
http://www.thesamba.com/vw/forum/viewtopic.php?t=540804&highlight=phn+jetting
we had drilled the idle circuit air bleed hole.

(second chart, the column dedicated to the 32 PHN 2 carb), we assumed it is the "alesage d'air de relanti" which is 1.5 in size. We have drilled it with a 1.2 mm precision drill bit, beacause that's what we had available (we can enlarge the drilling later if required).

Now, we are sill experiencing a problem: the car works and maintains a stable idle speed (and all the adjustments (idle speed and mixture) are functional) only if we unscrew the idle jet a couple of turns.
We are using however a later model idle jet - similar to the one used on PDSIT type3 carbs or the 30-32 series or type 1 carbs. That's because our PHN although NOS, did not come with an original IDLE jet.

So, can anyone confirm if the original Solex PHN idle jets are similar and interchangeable with other Type 3 and 1 idle jets, or do they have an unique tip profile?

Also, can someone post a macro picture of an original 32 PHN idle jet tip?


Thanks in advance.
_________________
1965 Sunroof Beetle
1972 Type 3 Squareback
1978 Skoda 105S

[EverettB]

Here's the one from a super nice 32 PHN-1 I have here:

I pulled one from a 32 PSDIT-2 I had sitting around - it's the same.
I also had another one from another used PHN-1 - it's the same too.
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[Pelle]

32PHN-2 uses an idle jet marked 1,8 which is different from the regular ones used on 32PHN and 32PHN-1 (similar to the ones used on 32PDSIT and beetles). The regular jet will fit the carburator but the car will run like crap. It idles like you have race cam and it runs lean. In theory you could drill a .55 jet to 1,8 but you are better off finding the correct part. Get in touch with some of the guys in the German forum www.generation-luftgekuehlt.de I'm sure there will be someone that can help you.

[Komissar]

Wow, in this case things are much clearer.
A 1.8 idle jet certainly allows much more gasoline+air mixture through the system, kind of similar to the effect we got when I unscrewed the idle jet.

I have also found a chart on this address, confirming the existance of an 1.8 idle jet.

http://type3.forumactif.com/t2508-carbu-32-phn

- No. 60, last position : "etouffoir de relanti, 1,8/12V"
_________________
1965 Sunroof Beetle
1972 Type 3 Squareback
1978 Skoda 105S

[Komissar]

Hello,

I have another follow-up question regarding the 32 PHN-2 carb.

1. Distributor - which is the correct distributor for this carb?
And is there a Type1 distributor with a similar advance curve that can be installed rotated by 180deg. and work with this carb?


2. How exactly the accelerator pump adjustment works? (to cure the flat spot). (We are running it with a later model SVDA type1 style distributor (installed rotated at 180deg. ) , timed at 30degres advance@ 3500 rpm. )
_________________
1965 Sunroof Beetle
1972 Type 3 Squareback
1978 Skoda 105S

[Erik G]

the fat cap distributor, as that carburetor was only a replacement carb, never factory on a car

Can't help you on the SVDA but I think you time those at full advance with the vacuum disconnected

hope this helps
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[ibjack]

[Erik G]

ok, that makes sense. That's much newer than the parts book

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[Donnie strickland]

[Komissar]

Thanks I will redo the timing settings. What I have done is setting it at 3500 rpm with the vacuum off (and the vacuum port capped on the carb).

So the ideea is that for a later-style SVDA distributor, the correct procedure is setting it at 7,5deg BTDC at idle, with the vacuum hose off (and the port on the carburetor covered) right?
_________________
1965 Sunroof Beetle
1972 Type 3 Squareback
1978 Skoda 105S

[ibjack]