Horsepower difference between DCNF's and IDF's?

[Speed-Randy]

Does anyone have any dyno numbers for instance a 2387cc with k8 cam, 9:1 compression, CB CNC ported heads, with say 44 IDF's and either 42 or 44 DCNF's?

[Speed-Randy]

Ok.... How about any motor combo? As long as it was the same motor with both carb set ups! Anybody?? Bueller? Bueller?

[56BLITZ]

I'm interested in this myself.
I had 42 DCNFs on my 1776 and I LOVED them! 75,000 miles and NEVER any problems!
I now have a pair of 40 IDFs for my new engine, and I see that C.B. Performance has "hop-up" parts for the little IDF Webers.

[nicolas]

can't comment on bigger engines. but on a 1776 with a webcam 218.119 i ran 40 IDF's with 32 vents and it ran great. i put on 42 DCNFs with 34 vents on and everything was smoother, better and i did get better milage. i never dynode it afterwards, but to me it must have had a better output as it did run better on the track as well. this was all done on a type3 fastback. i am planning on using the carbs again on a bigger engine for a daily driven type3.

[hotrodsurplus]

I can't vouch for comparisons but when I worked at Kymco in the '90s Ron Silva had a 2276 with 44 DCNFs in his notchback. I can't remember the cam but it was fairly mild--he had to protect the TIII fan after all.

We drove up to Bakersfield for the drags and he effortlessly clicked off mid 14s in mid-90-degree weather. Another time I remember him crowing about getting something like 32 or 36mpg at 60mph on the freeway. The DCNFs are very precise and well designed carburetors. I have a bunch of them because of his and other friends' experiences.

They just don't like a lot of lateral Gs (at least when mounted longitudinally) unless you modify the carb tops to prevent fuel from sloshing into the chokes. But how capable is a Cal Look car on skinny tires of generating lots of lateral Gs anyway?

 

[nicolas]

They just don't like a lot of lateral Gs (at least when mounted longitudinally) unless you modify the carb tops to prevent fuel from sloshing into the chokes. But how capable is a Cal Look car on skinny tires of generating lots of lateral Gs anyway?

 

thank you for that last comment. as i have never had an issue with carbs flooding, yes it may be possible, but it will not happen when you drive your car in a spirited way.

[Dyno-Don]

The DCNFs are very precise and well designed carburetors. I have a bunch of them because of his and other friends' experiences.

Hey Chris - Sell me a Pair!!!!!!!!!!!!!!!!!!!! 

[Fritter]

This is an interesting topic.  I have a Deano DCN kit on my current 1600, and this winter I plan on building a more beastly motor.  I kind of wanted to keep my 40 DCN's with the Deano manifolds and linkage, but I don't want to if I'm going to take a huge performance hit. 

It's funny, if you read the Fisher Hot Rod VW book, he says the DCN carb is the shiznit (1970).  Even more so than IDA's. 

I'm thinking the DCN's would work fine on a street 2 liter and have good drivability, mileage, etc with the smaller vents, but the top, top (above 6K) RPM performance would suffer.

This is where the firsthand experience of those who have "been there" is invaluable!  There had to be a ton of DCN/DCNF motors running around in the 70s......probably way more than IDA motors?

[TexasTom]

My brother ran 40DCNFs on his 2 liter way back when ... with W120, 40x35.5 valve heads, etc. it ran a best of 13.7.
My original 2110 with 42DCNFs ran a 13.4. I upgraded the heads (more port work by Fumio) and switched to 48s to run my first 12 ...

If you go back to the early Berg catalogs, 86-87 for example, they quoted airflow numbers for the different carbs:
42DCNF - 515 cfm
44DCNF - 530 "       
48IDA - 540 w/37 vents (vent sizes for DCNFs not listed)

42s were recommended for 16-1900cc engines, 44s for 1900 & over w/big valve welded heads and competition exhaust ... happy to say I have a set of each LOL

No flow numbers for the IDFs, although still around and readily available ... somebody flow one?

As for horsepower capabilities ... well, we know how much air they can flow ...

TxT

As per horsepower capabilities

[Speed-Randy]

Thanks Tom, I'm trying to decide carbs for the notch I'm building, and I refuse to cut the car to fit a turbo or a type 1 engine. So IDAs are out of the question, really leaning towards DCNF's, especially after seeing the flow numbers compared to 48's.

[danny gabbard]

How about some new tec fuel injection ?

[danny gabbard]

Something to think about, How about cutting some manifolds up and bring carbs inboard and make a taller engine lid to clear what ever carb you deside on ? Randy, Get somebody like greg to weld fan on your type3 motor. They dont like a lot of RPM from what I hear.

[Donny B.]

Ya gotta love those DCNFs..!  Like Tom I am fortunate enough to have a set of each...!

Gene told me that the DCNFs were the only carbs that had an idle circuit small enough that it could be opened up for correct use on the VW engine.  He said that most carbs were to fat on the idle circuit.  He told me that personally many years ago.  I have never run anything but DCNFs on my dual carb motors...!

[Cheesepanzer]

If you go back to the early Berg catalogs, 86-87 for example, they quoted airflow numbers for the different carbs:
42DCNF - 515 cfm
44DCNF - 530 "       
48IDA - 540 w/37 vents (vent sizes for DCNFs not listed)

42s were recommended for 16-1900cc engines, 44s for 1900 & over w/big valve welded heads and competition exhaust ... happy to say I have a set of each LOL

From what I recall (as I asked), the 42's ran 34mm vents, the 44's ran 36 vents, and as you noted, the IDA's ran 37's.  Really impressive CFM totals considering the overall size and structure of the DCNF.

I regret selling my two sets of 44 DCNF's.

[edcraig]

DCNF's rock!

[nicolas]

Thanks Tom, I'm trying to decide carbs for the notch I'm building, and I refuse to cut the car to fit a turbo or a type 1 engine. So IDAs are out of the question, really leaning towards DCNF's, especially after seeing the flow numbers compared to 48's.

they fit type3's perfectly due to their compact design.

[Zach Gomulka]

Thanks Tom, I'm trying to decide carbs for the notch I'm building, and I refuse to cut the car to fit a turbo or a type 1 engine. So IDAs are out of the question, really leaning towards DCNF's, especially after seeing the flow numbers compared to 48's.

they fit type3's perfectly due to their compact design.

Agreed.

[TexasTom]

If you go back to the early Berg catalogs, 86-87 for example, they quoted airflow numbers for the different carbs:
42DCNF - 515 cfm
44DCNF - 530 "      
48IDA - 540 w/37 vents (vent sizes for DCNFs not listed)

42s were recommended for 16-1900cc engines, 44s for 1900 & over w/big valve welded heads and competition exhaust ... happy to say I have a set of each LOL

From what I recall (as I asked), the 42's ran 34mm vents, the 44's ran 36 vents, and as you noted, the IDA's ran 37's.  Really impressive CFM totals considering the overall size and structure of the DCNF.

I regret selling my two sets of 44 DCNF's.

Yes, correct!
I've verified that information visually, although one set of 42s actually had 36 vents fitted.
Too bad 36vents were the largest offered (that I can find), especially for the 44! Could build a real sleeper! Of course, smaller vents were also available all the way down to 26mm.
Also, how cool would an FI engine with 46mm Haltech throttle bodies be? 

The thing I always found interesting, from a tuning standpoint, was the typical manifold height for the DCNFs. I've always wondered why they weren't taller to potetially build torque. I've made some phenolic spacers from 1" material to play around with next time I fit a pair ... we'll see.

If I had a T3, I'd definitely check into a pair of DCNFs! Pretty sure I have some manifolds around here somewhere ...
TxT

[Chris bugster]

Over the years I worked at Stateside Tuning, the best running engine I ever drove was a hot T1 with DCNFs. It was better than the fuel injected engines (my mother's then brand new Saab for example) around back then because it was just as smooth, but reacted to the gas pedal much better. I would love to have a pair of them now and would build an engine to suit them rather than getting something bigger just for the air flow capabilities.

[Dick Mitchell]

I had a 1915cc engine with a Web 86B, 42x37 heads, a few years back that was fitted with 40mm Dellortos and later 45mm Dells.  The engine performed very well, but was definitely "picky" and I was always tinkering with the carbs.  The car was always in good tune but still ran a bit harsh.  I've had a few other size motors before and after this one that included 48 IDA's but the one I can compare most closely to this one is my current engine

It's an 1800cc (74 x 88) Engle K8, ported heads and a 6-lb. flywheel.  I'm running 40mm DCNF's w/34mm vents and I couldn't be happier with the power and smoothness they give.  I've never built an engine that runs as nice as this.  And the power feels just the same if not better than my older, larger, more-carbureted 1915.   Once I set the carbs on my 1800cc back in June, I've done little to them since.  The DCNF's are compact, easy to tinker with (even though I rarely have to) and smooth in nearly every engine RPM.  I also like how unique they seem to be nowadays, but I think they'll be making a come-back.  And rightfully so  

I'd love to get a set of 44's in the future.  When it comes to anything other than 48 IDA's, I think the DCNF is the better choice, especially for a street car

[Dustin]

Hey Randy, I ran 42's for a little over a year on my 2054cc with CB CNC heads and engle 120 cam before swapping them out for 48 IDA's. I got 28mpg highway with the 42's and they were smooth throughout the entire RPM range. The only trouble I had with them was with the choke circuit, which I eventually fixed by tapping and chasing with a set screw.

I don't have any dyno or track numbers, but I didn't experience any top end performance improvement running IDA's with my "mild" combo. The difference was the distinctive gurgle of the IDA's combined with the added WOW factor in the engine compartment.

BTW, those DCNF's are still in service, trouble-free on a 2 liter type 1 bus motor.

Just my 2 cents worth! Carry on!

[Pedalpusher]

Hi, I have a pair of 42 DCNF's in sight, including unported manifolds and airfilters. As I have seen those carbs so rarely for sale I don't know what they usually sell for, is 500 euros good price for a set like that?

Thanks in advance
-Mikko-

[alstare84]

I bought this kit in August from ebay.com
http://alstare84.net/?p=736

I payed about 400$ (was a bid with a "buy now" option, the guy also had a single dcnf with deano manifold for less than 200€); shipped to Germany included duty taxes about 530€ but I suppose that I was very very lucky, considering that the kit is complete and the mainifold not ported at all.

[Pedalpusher]

I bought this kit in August from ebay.com
http://alstare84.net/?p=736

I payed about 400$ (was a bid with a "buy now" option, the guy also had a single dcnf with deano manifold for less than 200€); shipped to Germany included duty taxes about 530€ but I suppose that I was very very lucky, considering that the kit is complete and the mainifold not ported at all.

Now that sounds like a real bargain! Sounds like he was hoping to get rid of them fast with that price.

[Pedalpusher]

Hi,

Would any of you have any information of the "Berg Special" mods they did on the 42's? I've been googling on the internet for days but haven't found any real info, only some guesses.

Some suggested that these are the modifications:

1. Bigger aircleaner mounting studs.
2. Nuts on the adjuster screws.
3. Grind the numbers off the side.
4. Choke block-off plates.
5. Ball-valve needle and seat

BUT on the berg's site was line that said they were re-drilled and circuited specially for VW use on top of those mods.

If anyone have had the opportunity to inspect both the normal and Berg special DCNF's, I'd be glad to hear your opinions.

Really would like to have every benefit out of these carbs in use as i'm installing them over the winter and using them next season.

BR
-Mikko-

[Donny B.]

I think the do something like the third progression hole on IDAs.  Gene told me once that the DCNFs had a small idle circuit that could be opened to properly work on VW engines.  They do add the nuts on the adjustment screws.  They do not add the block off plate nor do they pin the enrichment valves against the seats.  I had to buy the block off plates and pin the enrichment valves myself. They grind the word Weber off the back of the float bowl as Gene wanted folks to know that they were his specials.  They did not come with the ball valve needle and seat.  I had to buy them extra and I don't believe they have them any more.

[Pedalpusher]

Ok, thanks for the reply!

So it sounds like it would be wise not to go and mess around with good carbs with myself then, with the opening of circuits and all. Folks have after all driven DCNF's without the mods and praised them.

The one mod that could be done easily is not one of the Berg mods but the extended "breathing hole" of the fuel bowl so that when cornering the car, the air correction jets would not drown of gasoline. But let's see what's going to be done over the winter.

BR
-Mikko-