Calibrating and tuning dual Weber DCD's
07-20-07, 09:00 PM
#27
My wife bought me 2 RX-7s
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Just an update for those who are interested:
Just took a run down to Regina for the local Solo II event. I figured on getting ~20 MPG...
I got 28 MPG.
Our crew also grabbed the five top spots at the event, with me trailing a Formula Vee and crazily modified Mustang on fresh v710's. I like these carbs. I like these carbs a lot.
Just took a run down to Regina for the local Solo II event. I figured on getting ~20 MPG...
I got 28 MPG.
Our crew also grabbed the five top spots at the event, with me trailing a Formula Vee and crazily modified Mustang on fresh v710's. I like these carbs. I like these carbs a lot.
07-20-07, 10:11 PM
#29
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i have had my dcd carbs for a long time and enjoy them very much... i recently made a couple of pulls on the dyno for the se rx7club meet in savannah... on stock ports with rb header and 2.5in. pipes all the way back my whp wasn't that great but i was glad to see that the rwt numbers were pretty high... i was running fairly rich and i haven't changed my plugs in a very long time, plus i need to change my timing sum...
07-20-07, 10:26 PM
#30
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http://www.youtube.com/watch?v=8FQBd92UyTU
check this out... this was a fourth gear pull, and it was just to get an idea of what the setup is doing... it has never been properly tuned to my engine but then again i have never really had any trouble out of it either... when you hear the motor bog down at first, that was because he loaded the dyno too soon... so he backed it off and hit it again... it doesn't do that on the street, ever!!! anyway you'll have a blast with them...
trochiod- hey man long time know hear... we haven't spoken in a few, but i am glad to hear that you got your setup put together and running... have you tried to order the k&n filters for them yet, or did you go with something other... i recently ordered two from k&n direct because noone else has them... wasn't to bad of a deal i think i paid $62 or something like that for both replacement filters, and 3day shipping from the west coast...
check this out... this was a fourth gear pull, and it was just to get an idea of what the setup is doing... it has never been properly tuned to my engine but then again i have never really had any trouble out of it either... when you hear the motor bog down at first, that was because he loaded the dyno too soon... so he backed it off and hit it again... it doesn't do that on the street, ever!!! anyway you'll have a blast with them...
trochiod- hey man long time know hear... we haven't spoken in a few, but i am glad to hear that you got your setup put together and running... have you tried to order the k&n filters for them yet, or did you go with something other... i recently ordered two from k&n direct because noone else has them... wasn't to bad of a deal i think i paid $62 or something like that for both replacement filters, and 3day shipping from the west coast...
07-20-07, 10:44 PM
#32
28 mpg, outstanding, I've only managed 22-24, but I still have a bit of final tuning to do. Fwiw, Holley air corrector jets work for mains on the DCDs. What size jets did you end up with on your primary and secondary mains and what afrs are you running? Did you make any changes on the air correctors?
I've become quite fond of these carbs too, particularly since the 1/2 bp is getting to the point that it's driving like an sp when the secondaries are closed. By the time the secondaries open up, the rpms are high enough to make use of all of that wonderful bridgy overlap and it's go go go.
I think my next move is to change the primary venturi to the smaller size used on RE's 12A sp carb and keep the 13B sized sp venturi in the secondary side. Only problem is that takes a special Weber tool on the DCDs, oh well, it's only money, right.
Dayton, both of my setups came with K&N filters, funny thing is one is tall, the other is slightly shorter. I need to find someone with a laptop so I can take the wb to the local 1/8th mile track and do some final tuning on afrs. Overall I'm quite pleased with them. No bogging, no flat spots, I can hit the pedal at any point in the rpm band and even cruise at 1500 rpm through town, push the gas and have a nice smooth acceleration.
I've become quite fond of these carbs too, particularly since the 1/2 bp is getting to the point that it's driving like an sp when the secondaries are closed. By the time the secondaries open up, the rpms are high enough to make use of all of that wonderful bridgy overlap and it's go go go.
I think my next move is to change the primary venturi to the smaller size used on RE's 12A sp carb and keep the 13B sized sp venturi in the secondary side. Only problem is that takes a special Weber tool on the DCDs, oh well, it's only money, right.
Dayton, both of my setups came with K&N filters, funny thing is one is tall, the other is slightly shorter. I need to find someone with a laptop so I can take the wb to the local 1/8th mile track and do some final tuning on afrs. Overall I'm quite pleased with them. No bogging, no flat spots, I can hit the pedal at any point in the rpm band and even cruise at 1500 rpm through town, push the gas and have a nice smooth acceleration.
Last edited by trochoid; 07-20-07 at 10:53 PM.
07-20-07, 10:52 PM
#33
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it makes 112whp at 102rwt... i was surprized at these numbers because of the way it pulls on the street... it sure feels stronger than those numbers, but the dyno don't lie!!!
07-21-07, 02:08 PM
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i recently spoke with mazdaspeed7 and he says he has the nessesary tuning equipment to tune them... i could always put it back the way it is... just take notes on were it is set before we start tinkering with it... on a side note i recently had my hood open and had someone ask me about the choke cables that i just have hanging in there... he wanted to know what they were for and why they were not hooked up... i just never bothered, because even in the winter in atlanta when it was freezing outside, i never needed them.. has anyone else needed their choke on the dcd setup???
07-21-07, 08:41 PM
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i have the parts to put it together... i was just wondering if anybody acually used it??? i have never needed to use it...
hey can we please keep this thread alive for awhile longer because there has got to be more than four of us out there w/ the dcd setup... or maybe we need a new thread just to see how many folks have and use this setup...
hey can we please keep this thread alive for awhile longer because there has got to be more than four of us out there w/ the dcd setup... or maybe we need a new thread just to see how many folks have and use this setup...
07-23-07, 08:48 AM
#39
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Hopefully soon there will be a fifth person with the DCD set up. I was lucky enough to get a Rotary Engineering engine (supposed to be dynoed at 225hp) with the twin 36/36 DCDs with K&Ns. The good part was the engine only has about 700mi on it and has been stored. The bad news is my friend tried to clean the varnish from the carbs and lost some of the parts. The last picture shows the pieces one carb had and the other didn't. I have since machined all the parts except the springs. I am currently trying anywhere I can to find them, including Pierce Manifold, Redline, and a Weber dealer in Italy (no luck so far). The fourth picture shows a close up of the carb with the top off and the question I have is; On the Rotary Engineering "Turbo Alternative-225hp" engine, should there be a jet in this side as well? Or did my friend lose some more parts? Both carbs were this way and he says he remembers them not having one in each threaded hole.
I also intend to use the choke cable and will probably lengthen the splitter cables using bicycle ones. My rememberances of this motor was much like Trochoid's in that it was powerful, smooth, and very streetable. I too would like to keep this thread alive since I will probably need some help tuning it after I get it in the car. If anyone has more information or comments please post them or send me a PM.
I also intend to use the choke cable and will probably lengthen the splitter cables using bicycle ones. My rememberances of this motor was much like Trochoid's in that it was powerful, smooth, and very streetable. I too would like to keep this thread alive since I will probably need some help tuning it after I get it in the car. If anyone has more information or comments please post them or send me a PM.
08-01-07, 05:06 PM
#42
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WELL THIS WEEKEND I WILL BE GOING TO HOT-LANTA TO PICK UP A RE MOTOR... I KNOW THIS HAS NOTHING IN THE WORLD TO DO WITH DCD'S, BUT I REALLY WANT TO TRY AND KEEP THIS THREAD UP AWHILE LONGER... JUST TO SEE IF THERE ARE MORE THAN FIVE OR SO OF US OUT THERE... OR HAS THIS SET-UP BECOME SO RARE THAT WE HAVE STRUCK GOLD???
trochoid- I THINK I REMEMBER YOU SAYING YOU HAD MORE THAN ONE SET??? ONE SET IS 12A AND ONE SET IS 13B??? HOW LONG DID YOU LOOK FOR YOURS???
trochoid- I THINK I REMEMBER YOU SAYING YOU HAD MORE THAN ONE SET??? ONE SET IS 12A AND ONE SET IS 13B??? HOW LONG DID YOU LOOK FOR YOURS???
08-02-07, 07:16 AM
#43
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I think I've got a set too,,,, just picked this Rotary engineering car up. And she's got em. Only problem is I haven't ever even seen my new car! At least in person. From what I hear she runs like a champ though.
08-03-07, 01:10 AM
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No problem Dayton, I am in Iraq right now and have a little under 3 months left here. So it's gonna be a little bit before I get to see her. I had the car shipped to my parents house in the meantime and my dad has taken her out once or twice. He said she runs great.
08-03-07, 09:19 AM
#48
My wife bought me 2 RX-7s
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My carbs have been running well, for the most part. I am having some problems while racing during hard, high-G turns with starvation, so there's still some work to do. Is there a trick to setting these floats? Maybe I've got the adjustment wrong...
08-04-07, 06:44 PM
#49
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i've never had to set mine... i did clean everything when i first bought them, but aside from that never had to much trouble... set it and forget it, been running every since... very rich, but better that than lean... btw this is dayton