Need some help with dual carburetors
 

See attached photos.
my fathers 1980 Mazda rx7 has dual 2 barrel Weber Tipo carburetors on it. I just moved it from Wyoming to Florida (where it has been sitting in a garage untouched for years) and to be honest, it’s been since I left for college in 1993 that I have touched a carburetor.

I dumped a thing of sea foam in the tank and filled both carbs with it, let it sit, and with some effort, got it to start, but it is very rough and will not idle. The Seafoam has stopped smoking, so I know that’s out of the carbs but still in the fuel.

I know the gas is very old and I’m sure the jets and float are gummed. I plan to remove as much fuel as possible and get a full tank of new gas put in with some marvel mystery oil in the tank.

Beyond that, I’m at a loss. I can’t find the model of these carbs to order a tune up / rebuild kit (assuming they still make them) and I’m thinking I need to rejet them with low altitude jets? Also, a how to guide on the adjustments for these things would be amazing! I assume there is an air/fuel adjustment or two on them, but I don’t want to just start turning screws. I’m really praying I don’t have to mess with the timing…..

so.. please help me !!! 😂

thank you in advance.
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well your hint is that Tipo is the Italian word for type, so the type of carb should be stamped on the pad below
that Rotary engineering dual DCD kit is cool!

you mean right here on these plates?….
https://cimg9.ibsrv.net/gimg/www.rx7...ab7b0fdce9.png

I think I found it. A Ferrari 250 Weber 36DCS?
https://cimg2.ibsrv.net/gimg/www.rx7...c1d80dd5c.jpeg

Actually. That one has some screws mine doesn’t.

looks like a DCD 36 maybe. Wish I knew for sure so I could order a rebuild kit for it. And maybe find the right jets for Florida

i'm fairly sure they are 36 DCDs, as said above. it's the old Rotary Engineering setup.

yeah I’ve confirmed that is what they are. Car starts and idles now but back fires and sputters when it runs. I don’t know enough about them to know how to fix them

I had the Rotary Engineering Dual 36 DCDs on my '83 RX7 with a Street Ported 12A. I still have the spec sheet from Joe at RE, see attached if interested. Float height adjustment was important as these had a tendency to flood under braking and when parked nose down a steep hill.
https://cimg6.ibsrv.net/gimg/www.rx7...2a39ed5e31.jpg

Those are in fact 36 DCDs and yes they are really cool.

Here is an exploded view and a parts list of what is available from Pierce Manifolds.

https://www.piercemanifolds.com/category_s/237.htm

I think they have rebuild kits as well, although you may not need them, your carbs most likely will get by with a good cleaning, float adjustment and a little fine tuning.
Most of the Weber books include the 36 DCD (some available in digital form online),

Several manuals here: https://foxed.ca/index.php?page=rx7manual#other

Thank you so much!

I downloaded the FSM. I’ve been reading up on setting the tuning for the engine and mixture on the carbs.

has anyone tried the Color Tune method?

Gunson G4171 Motorcycle Colortune Kit 12mm https://a.co/d/5JEAogh

I don’t have carb gauges or a timing light, so may as well buy the correct stuff the first time.

I am pretty sure I need new jets as the car runs very rich regardless of the screw setting.

its not really needed, for idle you just set it so it idles the best (highest rpm, highest vacuum)
its pretty simple, although getting two carbs to do the same thing at the same time consistently is the hard part

Any recommendations on how to learn how to do this? I’ve searched on here and google and still not sure what to do.

I assume I’ll need different jets and some vacuum gauges?

try this https://www.rx7club.com/1st-gen-gene...paper-1145099/
it really really really really helps to have a process before you buy stuff.

i have found if you just follow this white paper you end up with something that works really well

Wow. That was a lot to take in and some expensive equipment that I don’t have.

im going to start with the vacuum leak test. I have a fog machine. So I’ll use that method.
im not sure about buying a 500$ meter to set the fuel air mixture. May have to find a cheaper route or a friend that has one.

I would just open it up and inspect everything inside for corrosion. If nothing looks FUBAR strip it down and clean the carb body passages, accelerator pump nozzles, float needles or balls, the emulsion tubes, air & fuel jets. Inspect the floats and see if they still float. If any of these parts look unsalvageable add them to your shopping list along with 2 gasket sets and 2 accelerator pump diaphragms if they are not in the gasket sets. Check if any of the rod ends in the linkage are stuck or have play and buy them too if needed. If the engine ran good before and the engine configuration hasn't been changed (I.E. - Porting or exhaust changes) since the car last ran you should be good to go with the same size jets and tubes that were in there. You can balance the carbs with a cheap Uni-Syn tool ~$40: Instructions: https://edelbrock-instructions-v1.s3...brock/4025.pdf