I feel like reading all the old threads doesn't help on this. Anywho, usual story. 1984 12a, stock port. Still have a stock nikki but stumbles. Now I now have a complete RB exhaust. Which, by the way, the new power pulse is a piece of crap. Do not recommend.

So with that, I have in my possession a 2 or 3 Rotary Engineering DCD kits. I have no idea if any of the carbs are viable, but lets assume i need to rebuild them. Also i would need to check the jetting on each of these because i dont know what type of 12a they came from and they wiped the jet numbers. I do have a new set of 36/36 non progressive carbs in box i could start with but iirc RE used a 28/3.

The other option is to do something like an IDA. Flip side, id like a choke since this is a street car. So then im looking at the 45 DCOE. I know the 48 DCO is an alternative through Atkins, but not sure if i can add the DCOE cold start to a 48 DCO or not.

So yea, not sure what to do other than i will not keep the stock nikki. Not like we're clogging up the forum traffic these to discuss this.

 

For Weber parts I like piercemanifolds.com . The website is primitive, but the selection is good and they ship quickly.
You can get a jet gauge from them to find out what size jets are in the DCDs.

There's not really a choke on the DCOE The lever on the back actually opens another pair of jets to dump more fuel to enrich the mixture. I took them off mine because they leaked, apparently there's no gasket.
The 48 DCO does not have a provision for them.

48 barrels might be too big for a stock port. I tried choking down a 48 DCO on my mildly ported 12A and it wasn't very responsive.

Fuel pump should also be changed from stock for one that flows more.

How complete is the DCD kit? I'd go with that if you already have an intake manifold with throttle cable linkage.

 

Pretty complete. I acquired 3 complete sets over the years. Most of the issues with them was throttle shaft corrosion so between them i can make at least one good set. I would have to make a new throttle shaft for the other kits. Then obviously see if the 28/36 carbs were still good (or rebuild them) or just go with the 36/36 i have new.

 

 

i've always loved the IDA so that would have been my natural choice, but if you've got 3 sets of twin DCDs in 2023, then i would say you have to go that route.

 

May we ask what you ended up doing with regard to the intake options here?
Rotary Engineering specifically used the 36/35DCD progressive units for good reason.
Non progressive operation will difficult to jet for transition/progression phases.
The primary choke diameters were sometimes custom turned.
The jets were often re-used and drilled special which explains the missing value stamps.
Emulsion tubes were occasionally drilled with additional bleed holes, depending on the assembly (12A/13B, stock or street port).
We have recorded component values for a couple dozen of these.
If you decide to sell any of the DCD units, feel free to contact us.
Good day.

 

I've used RE 36DCD setups on 12A and 13B, stock port and ported. Always had great results -- the jets can be easily swapped out, fuel economy and performance are good, and they're a nice piece of nostalgia. Also the divorced choke setup works great for those of us in colder climates -- better than a butterfly.

BTW -- I spoke with RE back when they were in business, and they admitted that the "torque tube" spacers beneath the carbs were only there for physical clearance to other engine components. I eliminated mine many years ago, but it required a custom outlet on the water pump.

I'm reworking my 12A 36DCD setup, but progress is slow due to life events. I'll post pics when I make significant progress.