weber carb question

[nampus]

Hi there, I have a question about fitting a weber carb on a micra. Some of the guys here have fitted one, but what are the other changes you made to the engine? Is there a significant difference if you just change the carb, without changing manifold (in of outlet), cams etc?

Nampus

 

[bobsp16]

by just fitting the 34 ich weber carb will be far better than the standard one power wise.

 

[nampus]

and does this fit on the standard inlet manifold? The inlet manifold on the picture doesn't look very standard to me.
how much hp are we talking about here? and is it noticeable at high or low revs? Thanks for the quick reply btw

 

[Speedle]

yes weber do a replacment kit for the k10, the only k10 that would need some extra work to fit a weber to is the one with the ECC system commonly the super s and 1.2 k10's on a K reg plate. there is a guide i have done in the guide section on this but in your case i suspect it will just be the basic swap, its very easy to do

 

[nampus]

I've got a 1.2 super s. it's from 1991. I'm from holland so we don't have k reg here. How can I tell if the ecc stuff is fitted on my k10?

 

[SammoHung]

if you have a carburettor fitted then you wont have an ECU ("black-Box"). ECU's are mainly for managing fuel injected engines

 

[nampus]

this is not about an ecu, this is about ecc, some stuff that seems to be fitted to some k10's and it gives you some extra work when you replace the carb for a weber one.

 

[Andrew]

The ECC cars do have a ECU, under the front passenger seat (at least on UK cars). You also have a lambda sensor on the exhaust, the carb is significantly more complex, the distributor is different, and so on. It is a full engine management system, without injectors.

I personally am of the opinion that the Weber makes no difference to a standard MA10 or MA12. Well, no positive difference. I'd say it definately makes cold weather starting harder, and has a habit of not working quite right.

 

[Ed]

inclined to agree actually. Only any benefit if the stock carb is faulty or worn beyond repair.

 

[nampus]

first of all, sorry to sammoHung, I didn't know about the ecu. As far as I know I don't have the ecc stuff on my k10. there is nothing under the passengerseat, and the carb looks pretty standard to me. But I still don't have an answer now. Ed says it makes no difference. en Bob says it's a lot different power wise? Who is right?

 

[Andrew]

I'd say Bob is using it on a non-standard engine, and had rolling road time to set it up, probably by experienced people.

At the heart of the matter is the way that carb works - you need some form of restriction to create the pressure difference which draws the fuel in. The lower the air flow, the harder this is to do, so a single throat carb (the Weber) generally has the venturi designed for low revs, and then compensations to fuel flow are done with different jets and emulsion tubes. Multi-throat carbs like the Hitachi open different venturis as the revs rise as not to restrict air flow.

SU type carbs tried to get round this by using a moving piston to change the size of the throat, and it worked quite well. You will find them in quite a few performance applications.

 

[sonic]

SU carbs are so easy to work with and set up as well.

 

[Andrew]

Yes, I entirely agree with that. There are only a few parts to change on the SU, and you can change the fuel delivery across the load range just by filing the needle.

Pick up a Weber catalog... and it's all a bit complicated.

 

[bobsp16]

the weber is a far better performer all the way through the rev range over the standard carb even on a standard engine using all standard manifolds.