Weber DCOE advice (rebuild & repair)

[EricB]

I purchased a set of Weber 40 DCOE triples from some guy on ebay who told me they'd been off a car for only 6 months - seeing what I found inside makes me believe that while they may indeed have only been off the car for 6months the car they were on must have been stationary for years....

Th box they arrived in had been sat on by UPS and I didn't see right away that the manifold had broken at one of the balance tubes - anyways nothing a bit of welding can't fix.... so ANYWAYS... here's my question

take a look at the two detail shots below>

One is of a particularly grungy main jet which I've since had soaking in carb cleaner for days on end and most of this crud has yet to come off - would you all advise me to simply swap the jets out for new ones? all 6 main jets and all 6 idle jets look like this.

Also one of the ears on one of the top covers is broken (apparently when someone tried to pry them open to knock out the shaft the floater rotates on)... I found the broken piece at the bottom of the carb on tear down and could foresee JB wedling it back on in a way where it won't fall off again. I contacted Pierce Manifolds in NorCal and they are out of new top covers - I am sure there are other Weber places but I don't know of them.

Any advice would be most appreciated,

-e

[EricB]

here's the pci of the broken top cover...

PS: how do you attach multiple images in one posting?

[HS30-H]

Hi Eric,

I can see what you are up against, and I have been there myself!

I too bought some carbs on the vendors' description, only to see an archaeological artifact from the Dung dynasty turn up in the post...........

That broken part in your picture is rather serious. This is the mounting for the float pivot, and it will be difficult to repair properly. If you get it welded, the welder will need to be very skilfull and you will need to re-drill the hole for the float pivot spindle. Tell me what series the carbs are ( there is a number on the top cover of the carb after the bit that says "40 DCOE" ) and I might have a suitable spare body of the same series that you can swap all your internals on to. It is most important to get the same series, as all the internal drillings etc. are different for the different series.

Restoring the carburettors properly is like restoring vintage wristwatches. It is not easy, and you really need to have all the information and tools to hand. At least you CAN get all the parts OK. There are plenty of specialists in the USA - have a look in a magazine like Grassroots Motorsport for a supplier.

The round jet covers are not expensive, and a nice new set of three will make the carbs look much better. The "wing-nut" top cover fasteners are made of brass, and are also still available.

As to the emulsion tubes and jets - I would not put too much effort into cleaning them until you are sure that you are in the ballpark for your own engine. What were the carbs on before, and what are the currently-fitted emulsion tubes, main jets and air correctors? I can give you some baseline data for a stock-ish L24 with cam and muffler if you think it would help. You might end up needing new jets, in which case there is no point in scrubbing up the old ones. Certainly you should avoid poking any orifices with wire ( or get ready to see a doctor! ) as you will damage them for sure.

I would also pay attention to the accelerator pump rod stroke - which is very sensitive on this kind of carburettor and can change the driving characteristics completely. The "series" of the carburettor will tell you what was fitted in them from the factory, but not necessarily what is in them now ( somebody might have changed them ). These are all still available anyway.

Tell me what "series" they are and I will have a dig around and see if I have a spare body for you. I know I am a long way from you, but it might be easier in the long run..............

All the best,

Alan ( HS30-H ).

[HS30-H]

This might be of help to you;

[HS30-H]

And here's the other side;

[EricB]

Alan,

Thanks for the exploded view but I already had.

I've looked at my jets again and here's the numbers I have been able to get off of them. Don't know which means what though...

Idle jet holder: no stamping of any kind

Idle jet : 50°F9

Emulsion tube holder: 180

Emulsion tube: F2

Main jet: 130

I still need to get you the choke size and the series # for my particular DCOE. I will try to do that today.

-e

[HS30-H]

Hi Eric,

Glad you already had the parts diagram. Just wanted to help you identify the pieces that you have.

Here are the jet sizes etc. that I used on my mildly modified L24 with 40 DCOE-18 carbs ( 176 BHP at the wheels - not bad for standard valves and no porting ):

*CHOKES = 32mm ( 30mm also OK on such a small engine, as you need to promote good airspeed at low RPM for good off-idle performance and good driveability )

*AUX. VENTURI = 4.5 ( standard on most 40 DCOE carb series )

*MAIN JETS = 115 ( leaner is better - those 130s are too big )

*EMULSION TUBES = F2

*AIR CORRECTOR JETS = 175

*IDLE JETS = 0.50 F9

*ACCEL. PUMP JETS = 0.45

*ACCEL. PUMP INLET / DISCHARGE VALVE = 0.5

*NEEDLE VALVES = 1.75

*ACCEL. PUMP STROKE = 10mm

That accelerator pump rod stroke is very important for the "driveability of your car on such a mildly tuned engine. Make sure that it is right and you will certainly find the car easier to use.

Looks like some of your data already matches with this - so you are half way there. I would recommend a final "rolling road" dyno session to get the jetting spot on.

If you can find out the series number on the carb top, I can have a look in my garage and see if I have a spare top that I can send you to replca that damaged one.

Good luck.

Alan.

[wesuk]

Will you look for me too. I'm in Swindon. I broke it exactly the same!

Cheers.

[HS30-H]

Hi WESUK,

If you live in Swindon I suggest you go around the back of the HONDA factory and have a look at what they have in their dumpsters. You never know, you might find something interesting!

Joking aside, tell me what series carburettor you have and I will have a look in my garage at the weekend ( I keep my cars and parts 10 miles from home, not because I want to - but because I have to ). You will find the "series" number written after the type of carburettor, stamped into the casting on the top cover of the body. EG: "40 DCOE - 18" - in this case "18" will be the "series" number of the carburettor, and signifies the internal passageing / circuitry / standard jetting / pump stroke etc etc. Technically, most of the actual top cover castings will interchange on the 40 DCOE ( apart from the later "emissions" type ) - but you will want to have the right one on it if you can.

Like ERIC B - let me know what you have got, and I will have a dig in my garage.

Good luck,

Alan ( HS30-H )

[CPMaverick]

Hello, I was hoping someone could help me out with some dimensions for the Weber 40DOE or perhaps others.

I am building an EFI intake for a Formula SAE car. I'd like to purchase ram pipes (velocity stacks) rather than machinging my own. The Pipercross rampipes are sold for the Weber 40DOE, 45/48 DCOE, 40DHLA, and 45/48 DHLA.

I am wanting to use these bolt-in ram pipes on 1.5" OD and 1.42" ID intake runners. So I'd like a range of 35-40mm for the ram pipe outlet.

Any help is appreciated

Charlie Ping