Weber DCNF vs IDF, DCNF for type IV application Options

[Alapone]

Hello all,

I am relatively new to the world of the 914. I have been wanting to convert my (mostly stock) 1975 914 2.0l from FI to carbs since I bought it about a year and a half ago. I recently purchased, via an obscure but cheap ebay add, a pair of what turned out to be Weber DCNF 40mm carburetors and manifolds. I was under the impression they were IDFs (rookie move I know)...

I have done a little research on these carbs for type IV application and have read widely varied opinions on the matter ranging from "throw them away immediately" to "could be a nice setup". I have a set of manifolds that look as if they will match with the engine and if they do I will likely give these DCNFs a shot. I am told these DCNFs were primarily used on alfa, ferrari, fiat and vw type I and III engines for a variety of reasons and are not the ideal carb for the type IV. Having these DCNFs in hand though makes me think twice about starting from scratch looking for some IDF 40s or 44s. My main question is, can I run these DCNFs with my 2.0l without problem in proper tune? If these are an ok carb for the type IV engine does anyone know where I can get a set of manifolds?

Please excuse the rambling and/or inconsistent information gathered by a 914 newb. Any help with this matter would be much appreciated.


-Andrew

[Mark Henry]

I'm probably the closest thing to a DCNF Guru here and I say no, they are a bad choice for a 914.

The DCNF works well in a type one beetle/bus application for a cruiser type car. In fact for a performance daily driver, that you need to get decent fuel economy, perfect AFR and engine longevity out of it is one of the best carbs.
But once you add high side G-loads to the DCNF the carb starts to have fuel/float issues. A hard left in a 914 will result in the carb's completely shutting off.
Please keep in mind the a DCNF is a Lambo/Ferrari carb that is mounted 90* of the VW mounting, thus they are not affected (the same way) by these G-loads.
Also they are great in the type 1 as the barrel are a perfect match for the close together intake ports of a type one head, but this is not so great for the type 4, even in a bus.

So I'd say they work great in a type one, sketchy in a type 4 engine bus, but they really suck in a 914.
BTW the 1967 bus in my signature has real Gene Berg DCNF "42 specials" on it, That engine I built form a GB kit in 1991.

[DBCooper]

But once you add high side G-loads to the DCNF the carb starts to have fuel/float issues. A hard left in a 914 will result in the carb's completely shutting off.

So I'd say they work great in a type one, sketchy in a type 4 engine bus, but they really suck in a 914.

Mark, the DCNF's did have the problems you describe, which is why they weren't used much off-road. But I used them back in the late 60's-early 70's on autocross T1 VW's, first a bug and then a Manx buggy. Not super g-forces, it's true, but slicks so not insignificant, either. They were also used on the first years of the Super-Vee cars, which were sleeved down T4's, without problems. There was some trick to baffle the float or the fuel in the bowls. I'll be damned if I can remember it now, but a Vee racer showed me how on my carbs, and they worked. I've only used IDF's since, but there's a trick with the DCNF's and there should be somebody around who can remember what it was.

[Mark Henry]

But once you add high side G-loads to the DCNF the carb starts to have fuel/float issues. A hard left in a 914 will result in the carb's completely shutting off.

So I'd say they work great in a type one, sketchy in a type 4 engine bus, but they really suck in a 914.

Mark, the DCNF's did have the problems you describe, which is why they weren't used much off-road. But I used them back in the late 60's-early 70's on autocross T1 VW's, first a bug and then a Manx buggy. Not super g-forces, it's true, but slicks so not insignificant, either. They were also used on the first years of the Super-Vee cars, which were sleeved down T4's, without problems. There was some trick to baffle the float or the fuel in the bowls. I'll be damned if I can remember it now, but a Vee racer showed me how on my carbs, and they worked. I've only used IDF's since, but there's a trick with the DCNF's and there should be somebody around who can remember what it was.

Yep my DCNF's have all the Gene Berg tricks done to them, Grosse float valves, some mods to the circuitry, plugged enrichment circuit, they used a certain production number...I forget what all they did.

My carbs were built for my GB T1 2007cc (78x90.5mm) kit before wide band meters, I've had these hooked up to my wide band and they are dead nuts on right through the entire RPM range.