# Question about dual webber carburators...



## niky (Jul 20, 2002)

for any gearhead out there over 20... what's your opinion on dual webber carb sizes for a 1.5 SOHC Civic? 

(no flaming please about Hondas being crap... this is a side project while my car is getting suspension work...!)

we've just gotten dual carbs for my bud's 95 Civic, Webber 45s with 36mm venturis (this is the air bore before the individual throttles) and 146 nozzles...

the car gurgled like crazy at idle, drowning at 1000rpm but pulling like a mother between 2k and 4k... yes, we knew that the venturis were too big... but we couldn't get the right size at the time...

now, with 30mm venturis and 120 nozzles, it pulls well over 4000rpm, but at no other time... doesn't pull as dramatically as it did with the other setting...

Question is: which setting should we use? anyone have any idea which we should change back? the venturis or the fuel nozzles...?


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## himilefrontier (Jan 21, 2003)

That's to be expected.The smaller venturis provide a stronger vacuum signal at low rpm's to suction fuel out of the float bowls, while they become a flow restriction at higher RPM's.The opposite is true of the larger ones.I would look at the larger Venturi's but with a lot of attention paid to the idle and part throttle tuning. Also, what kind of ignition are you using?When does the advance come in and what does your timing curve look like?Did it run rich at low rpm's with the large venturi's or lean?Have you tried tuning with a wide band O2 sensor and a chassis dyno? There are a lot of parameters that can be adjusted with Webers and you probably are going to spend a lot of time getting it just right for the combination.I have never used them, but I know form setting up my Holley 750 and Edelbrock 600 that it is a lot more complicated than you would think.


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## niky (Jul 20, 2002)

we're starting to get into that  ... no, we can't tune the timing advance, it's a non-computerized engine... (i've tried to convince him to get the vtec D15B, but he doesn't want to lose his original block!) ...we did advance the timing, and that helped a bit... it would be nice if we could find the optimum venturi size... sucks that we have to pick one or the other... would be nice if we could add a pressure sensor and extra throttles that would add more air at a higher vacuum.

so there's no way to get that raw power without sacrificing low rpm ride, huh? bummer...


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## LRO (Aug 6, 2003)

*I dont use venturis but...*

Have problems with rpms between 2000 and 5000 , the car drowns. However, i obtain more power at higher rpms than using any venturis, in my case 34 venturis. I have a 44 phh mikuni setup. The difference is noticeable, but that range drowning is driving me crazy too. With venturis is so much slow!!


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## Lazarus_023 (Jun 3, 2003)

niky said:


> *for any gearhead out there over 20... what's your opinion on dual webber carb sizes for a 1.5 SOHC Civic?
> 
> (no flaming please about Hondas being crap... this is a side project while my car is getting suspension work...!)
> 
> ...



keee-ripes! aren't 45's a little big? maybe 40's would suit it a little better....


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