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

[Elliot Cannon]

I have weber 44idf's on my car and once I got them adjusted have been happy with them. I think you will find that the FI cam in your engine will not be compatible with carbs. Others more expert than I might also respond. (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/popcorn[1].gif)

[DBCooper]

Yes, you can. The DCNF's are an older design so when the IDF's showed up they were pretty much abandoned. The IDF's are more sophisticated, have better (more and finer) adjustabity, and are simply a better design. DCNF's aren't the carb of choice, but that being said they'll work fine. Try looking in aircooled VW forums, they were the carb of choice of Gene Berg (long ago) so there are still some in circulation there, and since the 914 engine is a VW all that advice transfers directly.

EDIT: I second Elliot's opinion, though, that you're generally much better off getting the fuel injection tuned than switching to carbs. Exception is when you're going with a hot rod cam, then you need carbs or a programable ECU.

[SLITS]

You read, I'm tired

[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.

[Alapone]

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.

Thanks for all the help here. So assuming that the IDFs are the way to go, am I still going to need to swap out for a hotter cam for the carbs to run well? I currently have no autox or track day ambitions or want for substantial performance improvement. Is the cam 100% necessary to go with the carbs?

[ThePaintedMan]

Thanks for all the help here. So assuming that the IDFs are the way to go, am I still going to need to swap out for a hotter cam for the carbs to run well? I currently have no autox or track day ambitions or want for substantial performance improvement. Is the cam 100% necessary to go with the carbs?

I like carbs, but only on cars where someone has already made the conversion or for strictly track-built cars. I think you'll find the consensus here is that you'll be much happier sticking with the fuel injection. Though primitive by today's standards, it works wonderfully when you have all your bases covered. Is it running currently? A working fuel injection is highly desirable with these cars, especially a 2.0.

[Alapone]

Thanks for all the help here. So assuming that the IDFs are the way to go, am I still going to need to swap out for a hotter cam for the carbs to run well? I currently have no autox or track day ambitions or want for substantial performance improvement. Is the cam 100% necessary to go with the carbs?

I like carbs, but only on cars where someone has already made the conversion or for strictly track-built cars. I think you'll find the consensus here is that you'll be much happier sticking with the fuel injection. Though primitive by today's standards, it works wonderfully when you have all your bases covered. Is it running currently? A working fuel injection is highly desirable with these cars, especially a 2.0.

Yes the car is currently running FI not sure which setup it is but I am told it is original and my car is a 1975. Aint broke don't fix it type of thing?

[ThePaintedMan]

Yes the car is currently running FI not sure which setup it is but I am told it is original and my car is a 1975. Aint broke don't fix it type of thing?

Precisely. The money and headaches you'll go through trying to get carbs to work right simply isn't worth it. Instead, spend a few bucks of that money to put in new fuel lines and seals for your 40 year old injection system. You'll be much happier in the long run, IMHO. Many of us who run carbs only do so out of necessity or because we received our cars with the conversion already done. Others like Zach, a moderator here, have endeavored to get their cars back to injection well, because it just makes more sense, not to mention power and better mileage.

[saigon71]

(IMG:style_emoticons/default/agree.gif)

I was in a similar situation a few years ago with my stock 2.0 D-Jet.

Especially with a stock cam, I would highly recommend taking the time to sort out the factory D-jet for your car. You will get the most out of your car that way...better HP, more MPG and generally better driveability. I took mine on a road trip last year and I was completely impressed by what a 40 year old fuel injection system can do!

Read this...this guy put together a wealth of information on D-Jet fuel injection. I used this as a guide for troubleshooting.

http://members.rennlist.com/pbanders/DJetParts.htm

Let us know what you decide.

[Alapone]

(IMG:style_emoticons/default/agree.gif)

I was in a similar situation a few years ago with my stock 2.0 D-Jet.

Especially with a stock cam, I would highly recommend taking the time to sort out the factory D-jet for your car. You will get the most out of your car that way...better HP, more MPG and generally better driveability. I took mine on a road trip last year and I was completely impressed by what a 40 year old fuel injection system can do!

Read this...this guy put together a wealth of information on D-Jet fuel injection. I used this as a guide for troubleshooting.

http://members.rennlist.com/pbanders/DJetParts.htm

Let us know what you decide.

Thanks Bob, I have been thinking about this for so long that It may be one of those mistakes I just have to make and experience to learn my lesson. I do have an old r bike w some uncooperative carbs so I have a sense for what trouble shooting them is as a process. Not much fun. Even knowing that I still want to do the carbs for some reason. I am beginning to see how you can end up down the rabbit hole here....carbs and headers leads to cam, leads to ported and polished heads leads to valves to pistons and rods and and......(not sure of the correct sequence) thanks for all the help guys. I will definitely let you know what I end up doing here.

[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.

[sean_v8_914]

gene berg specials had extra progression holes drilled in, 5 vs 3 that it came with.
they ar NLA

[Mark Henry]

gene berg specials had extra progression holes drilled in, 5 vs 3 that it came with.
they ar NLA

I know they are NLA...in 1991 I got one of the last "new" sets of 42 specials from Gene himself. At that time you could only get the 42 specials by buying a complete engine kit from Berg.
I believe my kit was a GBSKIT-3-78H, I have the invoice in my files somewhere. I paid $4500 for that engine, it been solid as a rock. I could easily part it out and get my money back on the samba.