TheSamba.com :: View topic

Mon Nov 10, 2003 12:18 pm

This is a small valve that is secured to the top of the left-side PDSIT carbuerator, just above the accelerator pump. It operates electronically, and it allows for richer-than-normal fuel mixture during warmup.

Can I operate the carb without it, without the carb leaking or do I have to plug up one or more holes?

Anyone know if a source for jets for the 32/34 PDSIT 2-3 carbs?

Any info appreciated.
Rich
'72 Westy

Mon Nov 10, 2003 8:03 pm

It is a complicated little mess of orifices and whatnot to deliver the enrichment to that valve and deliver it to the central idling circuit when it decides the engine needs it. Do you not like your enrichment valve anymore? Or did you take it apart to see what's inside and found out that the resistor *was soldered to the spade terminal? I'd leave it on.
Colin

Mon Nov 10, 2003 10:55 pm

Thanks Colin but my problem is that I have a set of carbs (73) that I intend on putting on my 72, and the left carb doesn't have this piece. It looksd as though it has not had this piece for awhile, and what research I have done indicates that I can run without it, that I simply would not have the benefit of the richer mixture it provides during warm up.

My understanding is that is open when cold and allows more gas to the idle mixture, or that it is closed when cold, restricting air flow and thereby creating a richer mixture. Whichever it is, it reverses position as the engine warms. I am still not positive if I need to plug the hole or holes. I have never seen one of these things.
Thanks again,
Rich
'72 Westy

Thu Feb 11, 2010 10:52 pm

again with the old threads...

For some strange reason I'd like to get this idle enrichment thing operational. its a hobby, right? :D

heres what mine looked like when I rebuilt my carbs....bad angle, but the resistor thing inside felt broken and spun freely.

this thing has come up in a few threads recently and my bus struggles to idle when its coldish out.

is there any repairing this thing? are operational OEM ones still out there or do these things just burn out by now?

Fri Feb 12, 2010 7:48 am

Mine did not spin freely, but had 0 ohms resistance, instead of the 65 required. (65 ohms is stamped on the front of the cover).

Couldn't source one locally at a yard, so I'm rebuilding mine. Since it's a bimetallic element, which just needs heat to operate the valve, and it can accept 12v, I figure I can rebuild it with some resistance wire.

OK, so I crushed my existing one and found that's how it was built. Resistance wire wrapped around a porcelain insulator.

I will post more info when I actually receive the wire, ordered from http://jacobs-online.biz/nichrome_wire.htm

Sun Feb 28, 2010 8:19 pm

My rebuild idea worked! Follow along:

Crush the original insulator to see how it was built:

Layout the parts to illustrate the rebuild - the red insulator was my first attempt at building an insulator from heat shrink tubing and JB weld. It worked, but was very difficult to do.

These are the items I used to make the second insulator. Yep, those are lollipop sticks :P

The lollipop stick proved to be too slick to effectively wrap the wire, so I coated the stick with the latex mold builder. This lets the wire "bite" into something and not slip around.

After I had wrapped enough resistance wire (I decided to use the 40 AWG) to get close to 65 ohms, I coated it in the epoxy. I mixed it and brushed it on with a small model paint brush. Then let it hang.

Here, you can see the wire wrapped around the insulator, under the epoxy.

After putting the enrichment valve back together, I test it by hooking it up to a 12v power supply for < 5 minutes. It opened the little valve, and after a few minutes of being disconnected, the valve shut again.

I'd call it a success.

Sun Feb 28, 2010 8:33 pm

You did an awesome job! isn't it a good feeling to FIX something rather than replace it or forget it. :D

Sun Feb 28, 2010 9:14 pm

My Hero, great work, and with pictures and everything - =D>

While yours is obviously a better route, im going to also trya slightly different rebuild - I called the local electronics supply and they have 12V 65Ohm resistors - if the size is reasonable and fits in the housing, they said it would produce heat....works maybe?

Mon Mar 01, 2010 1:32 am

Well the funny thing about that enrichment device is that it was a long walk to a short pier.

Because VW was struggling mightily to get HCs and CO down to an acceptable regulations mandate, the carbs were adjusted "too damn lean" for driveability, and that included the central idling circuit. The enrichment box there was to get it running, then get out of the way.

We are now well-beyond such high-wire balancing acts, and you can easily compensate for its lack of participation.

That said, I too had to get mine on the late great Road Warrior to work correctly. I had a simple solder job to do, the resistor itself was fine as were the bimetal and plug, after a half a million miles.
Colin