I have seen the SU bushings used on DCD's on old porsche's. You have to machine the relief, then the shaft slides right in. What diameter are the DCD's stock shafts?

In fact, I would just find bushings matching the shaft size and press them in. There's probably a machine shop local to you that can do this easily for you...

 

The standard shafts are 7mm. Oversized shafts, if they were available are 8mm.

I think it would be fairly simple to buy a metric 7mm bushing and drill the carb body to match the outside diameter of the busing and install it as you would an oversized shaft.

The bushing I found has an od of almost 9mm. If it were not workable to drill the carb out to 9mm it would be simple to machine the od of the bushing down to the 8mm that the oversized shaft would be.

 

I recently picked up a twin DCD setup, so this is interesting to me. Can you post some pics of your engine bay?

 

Yeah that also got me thinking about the carb body I haven't pulled the shaft out yet, but I'm wondering if it's ovaled the body of the carb.
Also that's what's really screwing with my head is, for it to get wore out it would have had to have ran, there for it should run and idle now, even if it was running like crap.that part doesn't make sense to me.

 

ok, im back working on these again, I had gotten a little discouraged with them and had to walk away from them for a little while... anyways.
Robert, I contacted the company you posted about that bearing you listed, and just waiting to hear back from them, just to double check that should fix it? im pretty sure theres enough room to drill the carb body to 9mm. just double checking because theres a $50 dollar min order for those little guys. thanks

 

Wow, Surly we can find a cheaper alternative!

Let me do a little searching, maybe we can find something from mcmaster carr or somewhere that will sell small quantities.

As far as assurance that it will fix it all I can say is that I would think that it would, but we are navigating uncharted territory so there is no way to be sure.

 

Thanks a lot for your help I really appreciate it. It's a shame Weber doesn't still make some way to fix this problem, I can't be the only person that's ran into this.

 

Here is a source: http://bearing.firstbronze.com/item/...=prod&filter=0

They are about $3.50 ea and it looks like you can buy small quantities, but they do have a $20.00 minimum order. My carb shafts are not worn yet , but maybe we could share an order to avoid unneccessary cost.

I am thinking the best route would be to buy the 6mm bushing, measure the od (its about 8mm)with a micrometer, use use a machinist numbered set of bits to drill the carb body out so there would be a pressfit, press the bushing into the carb body, then measure the shaft with the micrometer and drill the bushing out to give a tight fit to the shaft and assemble the carb as you normaly would. I will measure one of my spare shafts and examine the carb body to see how long the bushing would need to be the first chance I get.

 

That sounds fine with me if you want some to, You can send me a pm on the details on ordering them if you want to.

 

Please keep us posted of the progress here.
We have several of these carb sets, some of them with similarly worn items.
The accelerator pump bores tend to be a long term item.

Although we have recorded several slight variations for this
configuration for 12A Engine Porting, here is the most common -
Reference Numbers:
- - - - - - - - - - - -
Diagram Ref. No. = [x]
I.D. = mm/(Inches)
- - - - - - - - - - - -

Primary Choke [72] 25mm
Secondary Choke [72A] 32mm
Starting Air Jet [18] 150 1.50/(.059)
Starting Fuel Jet [19] 100F1

Idling Jet [22]
Primary 45 0.45/(.018)
Secondary None

Main Jet
Primary [26] 140 1.40/(.055)

Secondary [26A] 145 1.45/(.057)

Pump Jet [70] 70 .07/(.028)

Emulsion Tube Air Correction Jet
Primary [74] 230 2.30/(.091)
Secondary [74A] 270 2.70/(.106)

Emulsion Tube
Primary [75] F-9
Secondary [75A] F-9

 

Wear of the carb body where the throttle shaft goes thru it is common with these DCD carbs. I think a brass bushing would be a good way to go. But you would have to machine those holes perfectly round first.

I did reasearch a few yeas ago when I owned a set of DCDs that did this.... Weber sold an oversized throttle shaft and you drilled the body just a hair larger to accept it, they were hard to find I see still.

I never could get them to idle right with that vacuum leak, but besides that they were a great set of carbs. The small idle fuel jets would plug up rather often though, that was a drag.

 

Why dont you take them to a trusted machine shop and let them sort it out?