# Many Weber DCOE Questions



## vlksdragon (Jul 28, 2000)

Hello Carb forum,

I'm under the gun to put together a running setup in a '75 rocco within the next two months, however I have practically zero carb experience. I have picked up Des Hammill's book, and it has helped considerably so far, and I'm muddling my way through the FAQs, but I could use a little more experienced help.

Setup will be a bone stock 9a with dual weber 45s, operating at (mostly) sea level, with ambient temps ranging from 50 degrees to 90 degrees seasonally.

*First question:* I received a set of 45 DCOEs (pics below), but one of the covers says 40. I measured the bores, and they are both 45mm. I'm guessing the covers are interchangeable between 40s and 45s, and someone just slapped a 40 on the 45 at one point?

*Second question:* I see that jetting takes some experimentation, but I would like to get somewhat close before startup. What are recommended setups for a stock 9a?

Current specs on the 45s are different between the two, and are:

Carb #1 - 32mm choke, 130 main, F16 emulsion, 190 air, and 45F9 idle
Carb #2 - 34mm choke, 125 main, F9 emulsion, 170 air, and 45F9 idle

*Third question:* Since I don't know the history/condition of these carbs, should I just rebuild them now? If so, how difficult is a rebuild for a beginner?

I'm likely going to have more questions, but I'll start with these for now...


----------



## antichristonwheels (Jun 14, 2001)

the rebuild is not as hard as cleaning. A sonic bath is the best way to get them clean. Based on your comments, I would suggest you take these to a good shop and pay 200-250 to have them built for you.


----------



## vlksdragon (Jul 28, 2000)

antichristonwheels said:


> the rebuild is not as hard as cleaning. A sonic bath is the best way to get them clean. Based on your comments, I would suggest you take these to a good shop and pay 200-250 to have them built for you.


Can you elaborate on why I should have them built? I am operating on a tight budget (aren't we all?), and if I can save the $$.....not to mention I'd like to learn carb operation firsthand.


----------



## Boost_Retard (Oct 10, 2005)

i run dual weber 40 DCOE 2's on my 8V, and if you dont know what your doing, its much better to take them in and pay the money to have someone that knows whats up, build them right the first time. watch what they do if you get the chance, take notes.

i have every weber book under the sun to my knowledge, and reading it and making it happen are not exactly the same thing. you can do it for sure but there are so many tips and tricks that make or break the outcome, its hard to replace a guy with experience your first time out...

not to be a downer or anything but there is a good chance that you would end up hating carbs forever if you dont really know whats going on but decide to take it on yourself anyhow.

i was at the race track on the 20th and was having trouble with my dcoes, and a old boy from back in the carb days was watching my laps, and at the end of it all he came over and showed me some things that i would have never thought of..and things are running much better now..even though i know what im doing (for the most part) with these carbs.


----------



## IRDangerDave (Sep 22, 2010)

Boost_Retard said:


> not to be a downer or anything but there is a good chance that you would end up hating carbs forever if you dont really know whats going on but decide to take it on yourself anyhow.


Bingo. Webers are just as much science as they are an art.

I *definitely* recommend a thorough clean and rebuild. I'm mildly concerned because of the swapped float bowl cover and venturi/jetting differences that you might have two different series of carbs as well. Take your progression hole covers off and make sure the pattern and sizes match. If they both had the original jet covers it would be plain as day (see where it says 45DCOE13? 13 = series). If they are different series of carb, they won't play nicely together.

Also, not to be a downer, but assuming they are the same series, you have a bit of $$ to spend to get them on par for a baseline. You need at least two new venturis, two new emulsion tubes, and a good collection of mains and air correctors. 45F9s should get you started towards a good idle, but you MIGHT need to go up one. A good base for a stock 9A (it will run, but probably not all that amazing) would be either 34 or 36mm venturis (go 36 if you plan on any kind of head work eventually), 50F9 idles, 140-145 mains, 180-185 air correctors and I vote sticking with the F9 emulsion tubes. If you want, PM me your e-mail and I will shoot you over a copy of a damn good Weber tuning book.


----------



## vlksdragon (Jul 28, 2000)

Great advice all around. I know CIS very well after many years of experience, and I've also worked with a few standalone efi systems, so I guess carbs are the last frontier for me. While it may certainly be better to send them in to an expert, that wouldn't allow me to learn as much, and it also conflicts with the budget of this build. 

On IRDangerDave's suggestion, I pulled the progression covers and found that the DCOE-13 has 3 progression holes, as expected, but the other carb has only 2! Did the 45s ever come with 2 progression holes, and if not, is it possible the other carb is a 40 that was bored out to 45? 

I was definitely expecting/budgeting to change at least the two 32mm venturis, as well as the other assorted jetting. So I guess my question is now, should I get rid of the mystery carb and find another single 45 dcoe-13 to match the known carb?


----------



## IRDangerDave (Sep 22, 2010)

Your best bet is to either find another 13 (more progression holes = better) or sell the pair off as singles and find a matching pair. If memory serves there was anywhere from 2-4 holes, dependent on the series. In theory, another progression hole COULD be machined into the other, but I'm not a fan of trying to 'match' two different series.


----------



## antichristonwheels (Jun 14, 2001)

having access to a sonic cleaner is the best reason to have them professionally rebuilt. You can't get the real good carb cleaner that caused cancer in rats in California anymore. Additionally the standard cans of cleaner in the parts store, a DCOE won't even fit in them. You need the industrial sized can. 

If you have never rebuilt any carbs, you may have more problems than you can solve. I have rebuilt a bunch, lawn mowers, chain saws, carters, rochesters, holleys, and I have had Mikunis on an 8V and currently have DCOE 45s on my 16V truck. That being said I have a used set of 40s that I am getting rebuilt by a local professional specifically because he has the sonic cleaner, not to mention more experience than I. 

Also a set of carbs and a low budget probably aren't a good combination. I bought my setup brand new at a bargain price and I am still have around $1300-$1400 in everything. pumps, regulators, filters, linkage, new jets, it all adds up.


----------

