Is the Weber 40mm DCNF a good choice for an A15?, cause im getting it next week for a good price.

The DCNF differs from the DGEV / DGAV downdraft Webers ( 32/36) in the fact that it has only one shaft actuating the twin throats as opposed to two shafts in the DGEV/ DGAV downdraft Webers ( 32/36 ). Apparently these are simultaneous carbs, not progressive ( one throat valve opening at the begining while the second valve opens later on as the RPM increases) , the case of the DCNF being that both throat valves open at the same time like in the case of the 38 DGAS.

I have seen those, but never owned one. Those are supposed to be more performance oriented than the DGEV/DGAV Webers.

Perhaps someone has tried one of these Webers.

Yes, its non-progressive, it something like the 38DGAS...only thing slightly bigger venturi size. But the 38DGAS is a single barrel right??..

And i know that 40mmDCNF have better throttle response throughout the entire rpm range....

Any testimonies??.....How about the fuel consumption?...Any rough estimation of the fuel mpg?...thanks mates....

This is what I got "verbatum" from the Weber literature:
Quote:

Now, the DGAS is a simultaneous 2 barrel carburetor, similar to the DGEV/DGAV ( the A and E differences within the DGV series correspond to water or electric chokes respectively) but the difference relies in the sense that both throttle valves open and close at the same time , delivering more power, at the expense of a little more fuel comsumption. What you sacrifice in fuel consumption you get back in more power band when using a DGAS carburetor.

Both throttle valves ( one per throttle/barrel) are actuated , in the case of the DCNF carburetor, by a single shaft, one shaft moves, and both valves have to move along.

The DGEV/DGAV carburetor ,( as well as the DGAS ) ,all have two shafts, one for each throttle valve, so each valve responds to a separate moving shaft. In the DGEV/DGAV the shafts move separately, hence the name progresive , in progression. In the case of the DGAS , both shafts move in unison, hence syncronious.

I posted a pix of the DCNF in the photo album section.

Apparently the DCNF is a good choice. I do not have direct experience, so hopefully someone can illustrate on the DCNF with direct experience.

Thats great...Thanks alot mate....really really appreciate that.

You are welcome !

Good to know you are interested in knowing your equipment , that makes it more fun and also allows you to enjoy it to its fullest.

Yup, need to know what's the best since bigger aren't always the best....thanks again

Make sure you post pictures in here and tell us about your progress, very interesting to see a DCNF Weber set up in a Datsun.

If you can find / make the manifolds, you could have a dual set up..

Sounds like music......

Might sound like hole in my pocket with a twin DCNF setup. 40mm X 4 = 160mm.
Haha...

By the way, with this single DCNF setup, what cam profile do you suggest? Other plans for this engine is to port heads, flat top pistons & adding 3 ring washers at the valve spring seat. At the moment, im stuck at choosing the best piston ( flat top & lightweight is a must ).... :)

With all that work you can use a 270 or 300 degree cam. If you use a 300 or more cam, you will need oversized lifters due to the increased valve lift.

I want to see that DCNF ed Datsun!!!