jayroc

So, just what IS the advantage of having 2 carbs instead of one big one? My understanding is that one of the biggest carbs you can put on is a 51, but if you could run 2 32s or 36s, that'd be al the more fuel. Is that how it works?
Also, I've been doing a little reading about previous posts, and was wondering the difficulty in setup. Granted tuning is another matter, but just getting it up and running is what I'm concerned with. I suppose the OMP would be the biggest concern right off. Others?

680RWHP12A

none!!!what engine setup are you running?

jayroc

Stock right now. I'm look at getting a street ported motor or doing it myself around summertime.

Sterling

The only complaint I've ever read about was getting them both tuned perfectly together.
My dads old Healy had twin Mikkunis, and he had to spend alot of time keeping them in synch.

As far as the OMP linkage- That's nuttin 'tall. Alls it is is a wire. You can rig it on any carb you want. You just have to measure output @ RPMs as suggested by the Haynes or "Mazda Shop" Manual, and calibrate as such.

But I think things will be easier in the long run if you just go with the Weber. There's little gain by dual carbys cept it kinda looks neat.

jayroc

chicks dig the twin carbies.

680RWHP12A

i agree with Sterling... single Weber carb will work great!!! since the motor isnt ported go with a 45DCOE, you will love it!

riffraff

however, it the motor is ported.. can't you get better low end with two, without sacrificing the high end. smaller venturies and what not..

REVHED

Nice blanket statement with absolutely nothing to back it up.

Sure there can be advantages. I'm not sure about the 32/36 DCD's or whatever they are but a twin 48mm DCOE setup would be nice. It allows you to use a smaller venturi for a good vacuum signal at low rpm while still providing more than enough air flow for a great top end.

Now if only someone made a dual IDA manifold.

Hyper4mance2k

iTrader: (40)

gr8 nows WHO'S GONNA CLEAN UP MY JIZZ

680RWHP12A

yah im with you Hyper4mance2k.......

i dont know how it will work but i wanna see what its gonna look like!!!!!!!

riffraff

i will be more than happy with a dual wrap around dco manifold.

Wankelguy

There is also a tunability advantage as there is a seperate carb for each rotor. Plus, they do look bitchin'!

jayroc

What happens if one carb leans out or doesnt get fuel? Instead of the motor dying the one rotor would still turn the engine. What would be the harm in this?

680RWHP12A

leaning out one rotor could cause engine damage ,,,,where if you have one carb, and it leans out the car shuts down, wich wont cause damage as easilly if at all

Wankelguy

True, true...

But, one would need to be a complete idiot not to realize that he/she is running on one rotor and take the necessary action, dont'cha think?

680RWHP12A

YES, but he asked ???LOL

DriveFast7

iTrader: (1)

Everyone I've emailed said the dual carb 40 DCOE setup let the motor rev up like nobody's business. The kit is still available from the shop in Hollywood, CA who put it together, just do a search. They're on Varna Ave. Top End Performance is the name of the shop. Around $1200 all said and done! They said 10-12% more hp than a single big throat 2bbl carb and MUCH better throttle response.

I also talked to Fast Freddys who said the performance gain wasn't all that and not worth effort to tune and synch the carbs. So make your own conclusion.

Synching carbs isn't all that. They sell tools for that. My neighbor had no prob synching his dual SU's. I've talked to people with the old Rotary Engineering dual Weber 36 DCD and they needed synching just once a year.

European Motorworks in Hawthorne, CA on Prairie Ave had a dual down draft IDA style manifold in their display case a few months back! Someone step up to the plate and buy one and get it going.

-bp-

jayroc

Does anyone know of a good book specifically targeted at weber twin carb tuning? I'm looking through amazon, but I wanted a general forum concensus. I want to know the RIGHT way to do it, as opposed to what I usually do which is just try different random stuff and hope it works.
A good website would be beneficial, also. Most of what I found so far were for VWs.

Wankelguy

I think HP books put out a book specifically about Weber carb tuning, but I'm not sure if it covered any rotary applications.

bliffle

Those twin 40DCOEs worked great on my 62 alfa forever. Even when I overhauled everything else I didn't have to touch the Webers.

Looks to me like that Weber 45 downdraft might be good for the old 12A.

B