Deleting the Diaphragm Rod from Weber DFEV Electric Choke

[moss1972]

Hi All,

So the electric choke on the Weber 32/36 DFEV that came with my 79 Spider was not working. Butterflies were locked open. No high idle, cam wouldn't move. I opened the electric choke and found there is a notched rod about 2" long that rides on a couple springs, has a washer with a D shaped cutout and slides back into the diaphragm on the right of the choke assembly. The rod had rotated with the notch at a 45 degree angle which prevented the butterfly linkage from moving at all.

After studying this whole assembly the only thing I saw that could influence this "rod" was a small hole that vented the linkage chamber back to the diaphragm side of the choke. Possibly with an air passage into the carb? Still I could not determine how there was any possibility that this rod was meant to do anything but slide back and forth...NEVER rotate. I assumed the little D shaped cutout washer was supposed to hold the rod such that it only had the groove oriented flat side vertical so the linkage could move freely up and down as the heater coil in the choke influenced the linkage rod.

With this I went on to assume that IF this rod was doing ANYTHING all I could see it doing is POTENTIALLY FINE TUNING the closed setting of the butterflies by about 1/8" one way or the other. The rod had no more movement to allow for any other meaningful adjustments. So after losing the washer (oops) I removed the rod and springs. Now the electric choke is just the electric coil and the linkage. I put the diaphragm back but no rod or springs.

Well...this morning the choke worked. Needs to be tuned for the season a bit, as it engages a little too aggressively given the ambient temperature (butterflies closed too much for the OAT). But that's a piece of cake.

All in all - does this sound crazy to anyone running DFEVs?

[18Fiatsandcounting]

While we're waiting for Wetminkey (Todd) to add his input, here's mine: Could the device you describe be a choke "unloader"? These are fairly common on Webers, and this device insures that the choke plates don't remain completely closed as soon as the engine fires. If the plates don't open at least a little bit, the engine might start but then die due to lack of air.

Can you point out your part numbers on the diagram at:
http://www.carburetion.com/diags/3236DFAVDiaginfo.asp

-Bryan

[moss1972]

Hi Bryan,

Yes. Easily. It was part 47. Although I do not see the small spring or the little washer with a D shaped cut out that is supposed to cradle part 47 and keep it from rotating. Mine was rotating and blocking the butterflies from closing at all. It was locking them full open. As you described this unloader function that does make sense. As what would keep the heating coil from Fully closing those plates on a super cold day? I think you have turned me onto something there.

[wetminkey]

Gosh, guys,...I'm not new to carbs (!), nor Weber carbs, but the DFEV is new to me, and I've only been into it enough to ensure what jet-set it has, but I've not been into the choke mechanism.
Bryan has it correctly,...sounds like standard choke engineering.
Glad you've got it figured out! Todd.

[moss1972]

Gosh, guys,...I'm not new to carbs (!), nor Weber carbs, but the DFEV is new to me, and I've only been into it enough to ensure what jet-set it has, but I've not been into the choke mechanism.
Bryan has it correctly,...sounds like standard choke engineering.
Glad you've got it figured out! Todd.

I guess time will tell as fall approaches!

[wetminkey]

Naw, my choke works just fine. It's the jetting that's killing me, at 5000 ft elevation!
One interesting thing that I find: despite a fine working choke (butterfly plates), my DFEV does not have a fast idle cam that locks in place when the car is started,...I have to give it slight throttle for just a bit.
All other carbs I've encountered have had a fast idle cam that increased the idle speed until the choke began to close,...or reduced the idle progressively, with warming.
I've been too busy diagnosing my engine to troubleshoot it,...least of my problems, right now.
Best of luck with your's, Todd.

[18Fiatsandcounting]

Moss, yes, part #47 does look like part of a choke unloader to me. Weber's idea is this: The choke (whether manual or electric or coolant driven) closes fully to get the engine started, but then as soon as the engine fires, the vacuum created "unloads" (opens) the choke plates slightly, giving the engine enough air to keep running. My guess is that cars without this "unloader" function will still start and warm up sorta OK, although not optimal.

Sounds like you might have some parts missing from your carb, though???

To Wetminkey: Yes, a fast idle cam should be part of your choke mechanism. Not sure why it isn't there...?

-Bryan

[wetminkey]

I checked the DFEV exploded diagram carefully after my post, and I have found an adjustment screw WAY up under the choke mechanism. Interesting that Redline's installation instructions had nothing to say about it,...I'll investigate further when I can. Thanks.
piercemanifolds.com probably has the parts you need for your Weber's choke, moss1972.
Todd.

[moss1972]

Moss, yes, part #4 does look like part of a choke unloader to me. Weber's idea is this: The choke (whether manual or electric or coolant driven) closes fully to get the engine started, but then as soon as the engine fires, the vacuum created "unloads" (opens) the choke plates slightly, giving the engine enough air to keep running. My guess is that cars without this "unloader" function will still start and warm up OK, although maybe not optimal.

Sounds like you might have some parts missing from your carb, though???

To Wetminkey: Yes, a fast idle cam should be part of your choke mechanism. Not sure why it isn't there...?

-Bryan

Yes...after deleting the rod I did need to work the gas a bit to keep her chugging until the thermal coil opened the plates a bit then normal function resumed. Your assessment is the EXACT engineering I was looking for! You’ll make my dad happy. He insisted there was a vacuum function from the carb where I could see none.

Now to figure out how to get it back in spec without that missing washer. I have a few ideas.