Sgt Fox

iTrader: (3)

Those look like my carbs... Maybe I bought them off you?

High Speed Promotion

I have a set of these twin Weber on 12A bridge ported engine. Only the outer two intakes are bridge ported. The engine timing is about 24 BTC. The engine is very hard starting and fouls out spark plugs quickly. It will not idle below 2000RPM. I have reduced the main jets from 135 to 110. the air bleed jet is already 260, largest available. I thinking of reducing the idle jets, but there is only one step down from the current 45. The reduction of the Main Jets brought a slight improvement. The fuel pressure is 3 psi. The floats are at factory spec. This carb uses gross jets above the floats. I need suggestions as to how to the get the engine to idle . And of course start more easily. Does anyone have experience with this set up. These same carbs worked fine on a stock engine,

kirkosaki

I just bought a set of these 36 dcd webers off of ebay. Paid too much considering the shaft is wearing through the throttle body. Anyways!

My question is.. where does the pcv go on this setup? Can I run it into my brake booster vacuum hose? The diagram of the rotary eng. Install is good but doesn't show exactly where it needs to go. I can't pick out that note in red writing. Please help. Thanks!!

Also, can someone write out the process word for word from the manual on setting the timing? It's very hard to pick out.

oschool_3

We obtained one of the Rotary Engineering Weber 28/36 DCD carburetor sets from the company back in the late 80’s. It was a 12A stock configuration to start with and then was reworked (by R.E.) for use on a 13B street port.

One set is currently running on a Rx3 open track car w/ a 13B street port and another on a daily driver 85’ FB w/ a 12A street port.

Over the years we have compiled jetting information on fourteen of these dual carburetor sets, both stock and street ported, 12A and 13B. Several of these sets are also in storage. If anyone would like setup information regarding these units, feel free to contact me.

~ M

oschool_3

Pics

Sgt Fox

iTrader: (3)

Mine is running off the booster nipple.

elwood

iTrader: (1)

Thanks oschool_3 for the setup info.

I had a set on a REPU engine many years ago, and I liked it. I just dragged an'84 out of a 20 year hibernation, and I bought a 12A RE setup from a forum member a few months ago to replace the Nikki, which had a badly rusted linkage and butterfly mechanism.

It was in generally good shape, but the air cleaners were damaged.

I looked around craigslist and came up with a Magnalite aluminum roaster that was about the right size. I fabbed up a base plate and added studs to the center of the air horns. My plan is to mount a conical air filter in front of the radiator, then duct the air back to an inlet tube that I'll weld to the roaster. I have a similar cold air setup on my turbo '84, and it seems to work well.

oschool_3

Great looking adaptation.
I have found that a lot of people end up fitting K&N filters that are shorter than the original RE units, which encroach on the top of the air horns.
Your cold air idea is similar to one that I have mocked up for the FB, except I was going to move the overflow bottle, cut the air inlet into the passenger side of the radiator support and fab a box for the cone filter up front within the engine bay. The box would have drain holes for wet condition separation. Any which way, it is a great improvement.

elwood

iTrader: (1)

Yes, I also relocated the overflow bottle and plan to draw air through the right hand rad support. The difference is that I plan to mount the filter up front, instead of in-line.

I like your idea. There are a few off-the-shelf setups for that, which I considered years ago. Here's one from Spectre: 9831

elwood

iTrader: (1)

After looking at my conical air filter and a few of the aftermarket cold air setups, I decided to make my own. I made closeouts from aluminum and added a bulb seal. I cut a large opening in the RH rad support to supply the cold air box. The trickiest part was getting the contour of the underside of the hood. I used a combination of carpenter's contour gauges taped to cardboard mockups and clay. It seals against the hood very well.

rwatson5651

iTrader: (5)

very cool indeed!!!!

kirkosaki

Hey. Can anyone tell me why the 36DCD webers for the rx7 have no secondary progression circuit in the secondary barrels? There are for the Primary but not for the secondary. I noticed I get a slight starvation/hiccup when WOT is applied under 4500 RPM. I ordered some pump jet nozzles to see if that will help, But I am doubtful.

Let me know if you peoples have the secondary progression circuit or not. Thanks for any info

rxopel

Secondary progression of the type described was not part of the DCD design.
Without knowing other details for your situation, it is difficult to know (and only speculate) on what the shortcoming may be caused by.
12A or 13B ? Stock or ported (& what degree) ? Have you documented the venturi and jetting values ? What fuel pump and pressure ? Engine ignition condition and timing ? There are many things that could contribute to such a condition.
Many of these carb kits are third or fourth hand and the jetting may be changed. If you need original jetting values as Rotary Engineering supplied them, please forward a request with details of your engine and expected duty.

Justin Sane

Hey M, I'm Justin from Regina, I ha e a set of dual 28/36 dcds on my 12a stock engine. Its an 83. I was wondering if you knew the best fuel must setup how many turns out as well as timing. Idle timing in the destributor and the vaccuum timing while idling at 4000rpm you can text me 13069992081 or email justinsane_00outlook.com . thanks for any help you can give me again everythings stock I adjusted the carbs a bit she will idle but I can only drive a few blocks then she wants to die.

Sh00bs

iTrader: (8)

looking for stockport 12a jetting info for these guys

Gonna drop oschool_3 a pm, but figured a post would be good as well. just scored a set of these for $600 (w/ 12a mani)

kirkosaki

Here's some info if you didn't find it already:

https://www.rx7club.com/1st-generati...etting-917923/


I'm still messing with my Timing. Kinda worries me now haha. I'm going to set it back to 3 degree on Leading and 15 ATDC on Trailing at Idle.

Sh00bs

iTrader: (8)

i got the info, waiting to get the jets right now thanks

kirkosaki

Hey ! Does anyone know the exact Timing for these weber carbs? Do you have to adjust the timing by synchronizing the leading and trailing. for example, If I advance 1 degree on the leading I have to advance 1 degree on the trailing.

Racing beat suggests otherwise with the timing and says to keep stock timing. I'm confused!

Thanks for any insight

Sh00bs

iTrader: (8)

i havent ordered the jets for mine yet but id imagine go off stock timing... then slightly adjust and play with timing as needed. usually slightly advanced

t_g_farrell

iTrader: (1)

There is no exact timing for an engine or a carb for that matter. Start at stock and advance until
power drops then back it off a degree or so.

Sh00bs

iTrader: (8)

ordered my jets yesterday. went with 135 main, 45 idle, and my current set up should still have the 100f1 tubes in it. hopefully it'll fire up with the current air correctors that are in it. I got it to fire up with the bridgeport jets in it now (dk the size, the jets were blank when i pulled them last night -_____- ) but under 1800 it would die.
Just to confirm, going off the diagram on pierce manifolds, the idle jet is located inside of the bowl, correct? the diagram makes it look like it unscrews from under the bowl, which is clearly incorrect.

Sh00bs

iTrader: (8)

NEVER MIND nvm nvm! man i feel stupid. i guess it was dark and i didnt see the idle screw above the main... sigh

put the new jets in, fired right up after a few pumps of the throttle. idled fine, but at 1800... just need to adjust that today, hook up choke and throttle cables and should be good to go

elwood

iTrader: (1)

I've been using my stock port 12A as a daily driver for about a month, and it's awesome! Special thanks to oschool 3 for helping with setup info. Couldn't be happier with the overall performance.

oschool_3

Good deal ! Given a bit of attention, these carbs can be adjusted to give great overall performance and at the same time idle at 700 rpm, even with a rather large street port.
I much prefer a normally aspirated engine that will last forever than a high strung turbo motor that may lunch out under the wrong conditions.

kirkosaki

Does anyone know of a online store as to where you can get parts for the weber 36 DCD? I've found gasket kits on ebay, but I'd like to get the other parts like accelerator springs, throttle shaft springs, etc etc.