Intrigued, Weber DCD Carb..- is it possible?
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Thread: Intrigued, Weber DCD Carb..- is it possible?

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    Spaceman GTeglman's Avatar
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    Intrigued, Weber DCD Carb..- is it possible?

    Hello Gentlemen,

    I was intrigued by a reply form Commodåren in another thread where Weber 28/36 or 36/36 DCD was mentioned to be the best progressive down draft carb because of its changeable chokes. You should be able can to it on a 1,1 liter as well as a 3 liter engine. (Its only drawback is the horrible price, a new one costs between 6-700€).

    Should one (that would be me) think of spending that eye-watering amount greens on a carb. is it possible to eg. use a 36/36 DCD as a replacement for my current 32/36?
    In other words do any of you wizards have experience with the above mentioned carb. on a Opel GT?..- or are chances bigger that you'll just laugh and mock me because I should have know form the beginning that it's not worth the trouble on a CIH 2.0S, not possible at all, difficult, etc. etc.

    Main Q : Is it possible?

    Second Q : Have anyone tried, and what was the experience?

    Cheers

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    The 36/36 DCD was a popular replacement carb back in the day in Sweden and Finland when the original DIDTA, INAT or Varajet wore out or started making trouble. If it is worth the money I can't say, but I personally think that a 32/36 is a good and cheap alternative on a stock engine. But a DCD would be perfect for a modified large or small displacement engine.
    There are jetting instructions for a 36/36 DCD on a 19S here: https://www.misab.se/lista.php?kid=4-544-553-665-758
    Last edited by Commodåren; 07-04-2019 at 10:42 AM.
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    Spaceman GTeglman's Avatar
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    @Commodåren,

    Thanks for your reply and link to jetting instructions. From what I can find on the interweb the DCD36 is close to "endless" tune-able, and very very reliable. I'm not unsatisfied per say with my Weber32/36 and I'm not in immediate plans to change it, but I have serious thoughts of taking the engine out this coming winter to do a rebuild and if a DCD would be the cherry on the cake, I could be very tempted to do so.

    Anders.

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    Just Some Dude in Jersey The Scifi Guy's Avatar
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    What is your intended purpose or goal with a carb change? More power? More economy? More fine tunable adjustment? It sounds like this sort of mod would be to attain the 2 latter choices. I would think that a side draft(s) would be the max power option and certainly not the economy option. I really liked the Weber 38 I had, but it had a very narrow tuning window

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    Comparing a DCD to a DGMS/DGAS/DGES is like comparing apples to oranges since the DCD is progressive while the DGMS is simultaneously opening. Steinmetz claimed 10-12hp more with a pair of 36DCD's on a 28H Commodore engine compared with the original 35/40 Zenith INAT's.

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    Hi Gordo,

    You are right that I have to think thoroughly about the intended goal, and I also do remember that you where kind enough to PM me with your experience with the Steinmetz inlet manifold and a Weber 40 DCOE some time ago, thank you.

    The reason I was intrigued by the DCD 36/36 was based on @Commodåren qoute from another thread, and that it should be very tune-able.

    The 2.0S engine in my GT is in fair condition. Compression is fine, but the valve seals could be healthier and the main bearings must is worn. Maybe not yet excessively, but oil pressure when hot is just a hair under 2.5 bar when running normal speed, and steady 2.5 on the highway. Idle pressure just over 1 bar when hot.

    I have strangely enough got a promotion a few months ago (my employer must be desperate or mad ), and I can easily put money aside and have plenty for a engine rebuild this coming winter.

    A light tuning, maybe a ENEM Y12 cam could be on the wish list, but main thing is that it remains somehow sensible and street drive-able. No doubt I would be happy with more ooomph, but I'm on the other hand not looking to build a (race) engine that wont work unless I'm on a track, which I'm not!

    Last but not least, Danish MOT is quite a bitxx when it comes to "too inventive" engine mods. Do it discreetly, and it will pass. 2.4l engine with 2 x 40/45 Side Drafts and they will go ape. I actually think I have entertained you with that fact in the past.

    Cheers.

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    Just Some Dude in Jersey The Scifi Guy's Avatar
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    Well, I'm certainly no vastly experienced guru when it comes to carbs or engines. Take nothing I say as wise, learn-ed, wisdom. I just relate my brief experience with some of the more "exotic" Weber carbs and rare Opel engines. I drove a 32/36 on a 2.0 for 25 years and loved it. If I hadn't got talked into buying a 2.4 by OGTS, when I called them to buy a 2.0 a few years ago, I wouldn't have done hardly any of the theatrics with side drafts that I did in recent years. I also speak from the point of view of what's available and common and easy to get parts and know how for over here. I presume that there are far more people on your side of the pond who have more experience with DCD's, DCOE's, etc. and other "exotic" versions of Webers than we have over here.

    There's a nice looking FI carburetor called a "Sniper" or something that has it's own electronics that looks very interesting and might slip by the MOT. Since you are now rolling in Krone's and itching to do a mod, maybe something like that would make a nice Winter project.

    I myself am going to keep the side draft for a few more years and then I'll probably go FI also, probably with a Motronic on a 2.2.
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    I found some info in an old ENEM catalog about using a Y12 cam together with a 2" exhaust system and a Weber 36DCD on a 19S engine. The cam accounted for 12hp, the exhaust 6hp and the carb 9hp for a total of 117hp, my estimate is that with a 20S as basis the hp rises to slightly over 120hp. There were also jetting suggestions for the DCD, primary main 140-145, secondary main 145, primary aux air 200, secondary aux air 180-200, idle 50, chokes 27 for both barrels.
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    Gordo, you might not be a engine guru, (I'm not the right to, judge), but never the less you have had experience with the Steinmetz inlet, and you where the perfect gentleman sharing with me on a PM, which I really appreciate. Besides that you do not strike me as a guy who is exactly afraid of doing mods yourself

    Rolling in Kroner like Scrooge McDuck, eehhmmm not really , but no I'm not complaining. As sole responsible for the Nordic Countries I'm the first to the guillotine if things go south, so it comes with a prize.

    @Commodåren, would it be to much to ask if you could share the article from the old ENAM calatogue, maybe scan it and send to my private email or share it on this thread..- only if it's not to much trouble. Slightly more than 120HP on a (my) 2.0S sound exactly the amount of Oooomphh that would suite the "old bucket", and me.

    Cheers.

    \ Anders
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    I am not sure of the cost anymore, but I have a two barrel 38, 38 Weber carb. You have to enlarge the areas on the intake manifold to match the bottom openings on the carb. A carbide bit and a rotary tool will do the job in about 10 minutes. Since the Weber 38 is synchronized with both barrels opening at the same time, it has a lot of guts. I don't know about the tuning adjustments, took it to someone who worked on Opels. I have a 2.4 engine in it and needless to say it can scare me to death going 90 miles an hour with about half the gas pedal down.


    Bob
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    Detritus Maximus opelbits's Avatar
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    I agree with Bob on the 38 DGAS. Less than half the price of the DCD for a new one, even less for a good used one. On my basically stock euro 2.0, I saw a definite increase in MPG (went from 25mpg to over 30 mpg) and power (especially torque!) over the 32/36.
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    Intrigued, Weber DCD Carb..- is it possible?

    Quote Originally Posted by opelbits View Post
    I agree with Bob on the 38 DGAS. Less than half the price of the DCD for a new one, even less for a good used one. On my basically stock euro 2.0, I saw a definite increase in MPG (went from 25mpg to over 30 mpg) and power (especially torque!) over the 32/36.
    You are lucky on that one! I went from 30mpg with my 32/36 to 24mpg with my 38DGAS and now I have a mighty 18mpg with my 40 DCOE

    On the topic at hand though.
    I think the DCD would be really cool! I think you should do it. If you can swallow the price tag it’s worth it just to have something unique on your GT. Also it’s a much more tunable carb than a 38DGAS.
    You can go and enlarge a 38DGAS Venturi but here is no going back!
    With a DCD (or DCOE like me) you can put in big venturies in for the long road courses or autocross where you need more power above 5000rpm or quickly throw in a smaller Venturi for a smaller track that needs more power down low (or for the drive home). Just carry the main jets and air correctors you need and write down the idle mixture screw settings for your high rpm and low rpm tune.
    It’s really fun swapping stuff around for different courses
    Last edited by Knorm65; 07-04-2019 at 01:13 AM.
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    Detritus Maximus opelbits's Avatar
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    I wonder why that is? I think for me the MUCH improved low end torque meant I didn't need to rev as much to get going, fewer rpm's equals less fuel.
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    Quote Originally Posted by opelbits View Post
    I wonder why that is? I think for me the MUCH improved low end torque meant I didn't need to rev as much to get going, fewer rpm's equals less fuel.
    Possibly. Almost universally a bigger non progressive carburetor means worse fuel economy. It’s possible your 32/36 was tuned really badly. But above 30mpg is amazing even with a 32/36. You must be a very reserved driver with well tuned 38DGAS for economy.

    I am not a reserved driver at all. My Opels get multiple redlines per drive lol.
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    Senior Member The Cub's Avatar
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    Quote Originally Posted by opelbits View Post
    I agree with Bob on the 38 DGAS. Less than half the price of the DCD for a new one, even less for a good used one. On my basically stock euro 2.0, I saw a definite increase in MPG (went from 25mpg to over 30 mpg) and power (especially torque!) over the 32/36.
    Interesting, that’s the first time I’ve ever heard of the 38/38 getting better mileage than the progressive carbs. Can anyone else who’s got the same set up back that statement up? I’ve heard on average they get 18-22 mpg on a 1.9 or 2.0 with a 10% increase on the HP, and that’s a good power increase for a bolt on item. The trade off being it costs you a little more at the pump. That’s been the reason why I’m in no hurry to get the DGAS.
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    Intrigued, Weber DCD Carb..- is it possible?

    My understanding of carburetors still has a lot to be desired so take this with a grain of salt.

    A 38/38 could, on certain engines, use a bit less fuel because the lower velocity of the air going through the larger Venturi pulls less fuel in.

    However a progressive carburetor like the 32/36 will always be more fuel efficient at cruise when tuned correctly ie. Correct jets and the secondary closed at cruise.
    A 38/38 is drawing fuel from both barrels always and just doesn’t have the same efficiency.
    Last edited by Knorm65; 07-04-2019 at 01:42 AM.
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    Just Some Dude in Jersey The Scifi Guy's Avatar
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    I had both. I had a 32/36 for 25 years and always got 25mpg no matter what I did. I could drive like a granny or floor it all day long and I always got 25mpg. My experience with a 38 was on a worn out 2.0 with a bizarre cam for about 4000 miles. I loved the hp increase and the throttle response. I probably got 20-23mpg with the 38 and loved every second of it. That carb responded very well to trimming of the spring in the cover. I could punch the pedal to the floor when idling at 800 at a red light with my automatic and I would happily spin the tires and roar off into the sunset.
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    Quote Originally Posted by Knorm65 View Post
    My understanding of carburetors still has a lot to be desired so take this with a grain of salt.

    A 38/38 could, on certain engines, use a bit less fuel because the lower velocity of the air going through the larger Venturi pulls less fuel in.

    However a progressive carburetor like the 32/36 will always be more fuel efficient at cruise when tuned correctly ie. Correct jets and the secondary closed at cruise.
    A 38/38 is drawing fuel from both barrels always and just doesn’t have the same efficiency.
    I seem to recall reading on this forum that a 38 Weber could get better fuel economy if tuned correctly because of better fuel distribution. I think the potential may be there for better fuel economy but I don't think many will be installing it for that reason. I still haven't settled on which carb to run as I tend to like the way my 2.0L accelerates a little too much.


    Harold
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    Project 1450 supporter... Site Supporter RallyBob's Avatar
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    I had a 1973 Ascona with an internally bone-stock low compression engine, with 32,000 miles on it.

    It had a 32/36 DGV fitted, and a Pertronix with a Bosch red coil. It got 24 mpg, exactly what it was rated at new.

    I built a 2.0 liter engine for it with a big-valve 1.5 head, a fairly hot solid cam, 2” exhaust with a Sprint manifold, ported intake manifold, and a 38 DGAS.

    It got 22 mpg highway. 14-15 mpg racing.
    It was 6.1 seconds faster to 60 mph than stock. It gained 38 mph in top speed.

    Granted, I had to run 93 octane in lieu of 87 octane, but I’ll take the 2 mpg hit for the performance gained.

    It all comes down to the tuning. Oh, and high compression engines always get better fuel economy too.
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    I personally see no reason in running anything but a Weber 38 dgas. They are inexpensive to buy, perform / run amazing and I easily get 25 + mpg on hwy out of my modified 2L with 4 speed.
    Last edited by Vincent; 07-04-2019 at 10:23 AM.
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