WEber Internal spring

[Zedyone_kenobi]

I have been chasing a sticking throttle on my Webers for a while now. Every sense I got back from the rally actually. I have replaced my 5/16" rod ends with 3/8" rod ends and actuator rod. Very beefy, I am happy with these! I have gone with a new LoKar stainless cable that is smoothly run to the carbs.

I was still getting sticking and the effort to push the pedal was HUGE and felt like it was moving through syrup. NOt good. It actually felt like I had a rubber band attached from the pedal to the carbs instead of a wire cable. Humm why could this be?

Carb number one was the most likely culprit. When I removed the actuation ball rod ends and just blipped the throttle on one carb at a time, the idle retuned wonderfully. However, if I just push lightly on each throttle lever on each carb (say 5 degrees or so), it stuck there on each carb! I had to manually push it back to idle on each carb. Now these carbs are not old. The nuts on both sides of throttle rod that are attached to the butterflies are not overtight, but they may be off center. I have not checked that.

My question is can the internal return spring be easily replaced? Or is it more likely I bent the throttle plates or throttle rods inside each carb? I do not think this could have happened, as I was extra careful to set my throttle stop inside the car to not over rotate the carbs.

But that is not really the issue.

THe issue I want you weber heads to help me out is, what would cause an individual Weber carb throttle lever to stick open without anything attached to it?

[LeonV]

I have the same problems with my old DCOE18s. It's likely stiction within the bearings, throttle rod, butterfly-to-throat, etc. I haven't done much to alleviate it as I've been content with my throttle return.

I went as far as the change out the internal throttle returns for new ones. It wasn't too difficult but don't expect it to be a piece of cake. That didn't change a whole lot. I've done the same blip one carb at-a-time test and they all failed to completely return to idle.

I said the hell with it and just set up the linkage as best as I could.

Thinking more on the throttle mechanism, there are two springs in there fighting against one another: the return spring and accel pump spring. I haven't done so, but I'm curious how much of an effect removing the accel pump springs would have on throttle return. This would simulate getting a slightly stiffer return spring.

[Zedyone_kenobi]

Well what you could do is put a return spring on each carb individually. That way you can eliminate the single return spring. I may look into that. I may pull off a carb to see if I have any buildup of gunk that is making things get sticky.

[240260280z]

I think it could be the A vs. C mechanical advantage in another thread. You should experiment.

Here is Weber DCOE internal Spring data:

Weaker

47605.012

47605.027

47605.009

Stronger

You can buy the strong one here:

Weber Throttle SPRING, Shaft Return

[LeonV]

I think it could be the A vs. C mechanical advantage in another thread. You should experiment.

Here is Weber DCOE internal Spring data:

Weaker

47605.012

47605.027

47605.009

Stronger

You can buy the strong one here:

Weber Throttle SPRING, Shaft Return

Phil,

What we're talking about happens with the linkage totally disconnected! Disconnect the linkage, individually blip the throttles and see if they drop back to idle. Mine hang. Good link on the return springs. I'll have to look back and see what I ordered, but from memory I got the stiffest ones available at Pierce.

[Zedyone_kenobi]

I saved your pages from the other thread Blue, THanks, But What Leon said was right. My linkage is awesome and feels great, right up until you attach it to the carbs. I am afraid I may have to pull them out and see what is worn or what is dirty to make them hang. I absolutely hate it when I come to a stop and the engine is still at 1700 rpm. Makes you feel like you drive a jalopy.

[240260280z]

OK sorry got it.... just going crazy here in terminal A at Newark ......half reading half feeling hot and uncomfortable argghhhhhh.

The Z I restored seemed to develop the same problem after 500mi.

We are going to address it in a little over a month. Trying the stronger springs is a first step. (FYI the carbs were rebuilt with newer springs from Pierce but they were the 47605.027 medium ones)

Edited March 16, 2013 by Blue

[Captain Obvious]

Don't know if it's applicable or not, but I just went through something very similar with the butterfly on my FI throttle body. No linkage connected, blip the throttle, and doesn't always return to idle. Worse if you hold it above idle and then release it slowly (instead of a "blip").

Most interesting thing about mine was that it only did it when there was engine vacuum present. With the engine not running, it always snapped hard clean back to the adjustment screw stop.

I think I have tracked mine down to worn through hard chrome plating on the throttle shaft which has exposed the gummy soft steel underneath. This soft steel of the shaft does not slide well against to the soft steel of the sleeve bushing pressed into the throttle body. I believe this soft steel to soft steel contact only occurs when engine vacuum pulls the butterfly towards the intake manifold and that's why it doesn't do it with the engine off.

In the end, I wrapped my return spring another wind around the shaft and called it a day. Doesn't fix the problem, but seems to fix the symptom. If it gives me any more trouble, I'm going to mount hardened bearing surfaces on the shaft and maybe swap out the soft steel bushings for acetal. Anyway... Way too much about me...

So does yours only stick while the engine is running, or is it at all times?

[Zedyone_kenobi]

I may have found a solution from some Aston Martin guys in the UK.

The way I see it the only way to really get around this is to apply a spring force directly to the actuation arm on each carb. So that means individual return springs. The original OEM one in the inside of the carb cannot be relied on after a while when things start to wear.

So I was digging around for folks with the same problems, and thank goodness the automotive Gods have created many a sweet straight 6 in the past that webers fit.

THis actuation arm has an integrated lever arm for a spring attachment. Now today I fabricated a small plate see below:

The rod end holds the plate in place between two nuts (not shown). This is held off to one side and has a hole drilled in it to attach a spring. If you place these plates on the rod ends, they provide a perfect connection to that lever arm up there and PRESTO, individual throttle springs for each carb. The advantages are numerous. Guaranteed return of each throttle lever. Less clutter on the Actuation rod and throttle cable. Most likely much smaller springs can be used so the ultra heavy throttle pedal feel that some of us get would be eliminated!

Needless to say I am ordering these lever arms AND fabricating two more plates!

Edited March 16, 2013 by Zedyone_kenobi

[Zedyone_kenobi]

Amazing that you posted that. Mine acts the same exact way. With the engine off it snaps back immediately. When warm and running it seems to want to hang.

I would not be surprised at all if the shafts were worn a bit. But these carbs only have about 2000 miles on them. Seems kinda early. But my symptoms match yours perfectly.

[240260280z]

Thus it seems to be air flow related. I am guessing the flow past the mostly closed throttle valve is too great, or the vacuum is pulling hard where the seals are and causing resistance

Maybe the throttle plate has to be cracked open more and a smaller jet with less air correction used. This will prevent the TV from having to return so far.

[Captain Obvious]

Amazing that you posted that. Mine acts the same exact way. With the engine off it snaps back immediately. When warm and running it seems to want to hang.

Cool. Was a shot in the dark just hoping it might ring a bell. I had a hard time convincing myself that vacuum had anything to do with it. I kept telling myself that the vacuum force on the butterfly should be balanced. As much force should be pulling on the top trying to open it as pulling on the bottom trying to close it. So I started looking for some other non-balanced phenomenon and ended up with the gummy steel to gummy steel theory. It's still a theory, but one that I have experimented with a little using a shop vac and blue marking dye. I can pull just enough of a vacuum with the shop vac to get it to show up a little on the bench.

So, I would be a little disappointed if you've got enough wear to cause this kind of issue after just 2000 miles though. Makes me think it should be something else.

Did you ever see my round tops with the integral return springs on the shafts? Did I ever show them here?