Twin 40DCNF ..

[plasticblack]

Does anybody out there have some practical/historical info on Twin 40DCF's please?

I'm considering a Twin DCNF set up and wanted to get some info on exactly what this carb set up might have been paired with engine wise (1641,1979,1776, 1835)?

I'm leaning towards an 1835, but am very interested in any history people can bring to influence that decision though.

Any info on linkages etc would be very welcome.

All and any information gratefully received.. 

[PIMPPRIDE]

( opps ) 

[plasticblack]

( opps ) 

Not Sure What this means exactly..

[PIMPPRIDE]

sorry, I posted to the wrong thread... 

anyhow, when your saying twin DCNF's are you talking 4 carbs or just 2 

that part is confusing a little... I have a pair of 42 DCNF's on a 1914cc type 3 if it helps any... the linkage is the old tayco style I believe you can get it from Bugpack still ( or a Bugpack supplier ) and the manifolds are BERG... last I knew, they still offer type 1 and type 3 DCNF manifolds...

Anthony / ISP WEST

[Zach Gomulka]

Think of it no differently than a pair of similarly sized IDF's or DRLA's. Will work on anything from 1600 to a mild 2 liter.

[plasticblack]

Think of it no differently than a pair of similarly sized IDF's or DRLA's. Will work on anything from 1600 to a mild 2 liter.

Great info thanks.. 

I'd really like to use the old carbs as it suits my project better than IDF's. If I can bag the DCNF's I'll be very happy indeed.

Thanks. 

 

[Jim Ratto]

A good friend of mine is running dual 40DCNF on his 88 x 74 Type 1, Engle K8, Jeff Denham 40 x 35 heads. I know it took some work to get the intial tune set up. The acclerator pump bell cranks might need room to swing in an early bodied car. Knowing that, if your engine bay is tight, you might want to consider a 69mm motor to help keep engine width tight. The fuel line entry points are a little more cumbersome than IDF/DRLA or 48IDA. The venturi sizes that are available for the 40DCNF go bigger than what I have seen for 40IDF but probably on par with what's available for DRLA. DCNF jets and emulsion tubes are unique so availability can be tricker than mains/tubes/air correctors for IDF as they are same as DCOE and IDA. The DCNF float design was originally set up to have float pin in same axis as the axles of the car so they do not like G forces when mounted in same plane as crank on a VW.

[plasticblack]

A good friend of mine is running dual 40DCNF on his 88 x 74 Type 1, Engle K8, Jeff Denham 40 x 35 heads. I know it took some work to get the intial tune set up. The acclerator pump bell cranks might need room to swing in an early bodied car. Knowing that, if your engine bay is tight, you might want to consider a 69mm motor to help keep engine width tight. The fuel line entry points are a little more cumbersome than IDF/DRLA or 48IDA. The venturi sizes that are available for the 40DCNF go bigger than what I have seen for 40IDF but probably on par with what's available for DRLA. DCNF jets and emulsion tubes are unique so availability can be tricker than mains/tubes/air correctors for IDF as they are same as DCOE and IDA. The DCNF float design was originally set up to have float pin in same axis as the axles of the car so they do not like G forces when mounted in same plane as crank on a VW.

I don't envisage space being an issue at present. I am thinking of a 69mm motor for sure. Most likely 69 x 88 (1679) Possibly 041 heads etc..

The DCNF's are right for the period and would be great instead of IDF's. Thanks for the factual info here Jim, it's really good to know that the DCNF's are running strong in your friends ride.

[Tony M]

I work on a notch with a 1835cc and dual 40 dcnf's - work great - i did not tune them to start with but could get jet sizes and such if you need.

  Tony

[Jim Ratto]

A good friend of mine is running dual 40DCNF on his 88 x 74 Type 1, Engle K8, Jeff Denham 40 x 35 heads. I know it took some work to get the intial tune set up. The acclerator pump bell cranks might need room to swing in an early bodied car. Knowing that, if your engine bay is tight, you might want to consider a 69mm motor to help keep engine width tight. The fuel line entry points are a little more cumbersome than IDF/DRLA or 48IDA. The venturi sizes that are available for the 40DCNF go bigger than what I have seen for 40IDF but probably on par with what's available for DRLA. DCNF jets and emulsion tubes are unique so availability can be tricker than mains/tubes/air correctors for IDF as they are same as DCOE and IDA. The DCNF float design was originally set up to have float pin in same axis as the axles of the car so they do not like G forces when mounted in same plane as crank on a VW.

I don't envisage space being an issue at present. I am thinking of a 69mm motor for sure. Most likely 69 x 88 (1679) Possibly 041 heads etc..

The DCNF's are right for the period and would be great instead of IDF's. Thanks for the factual info here Jim, it's really good to know that the DCNF's are running strong in your friends ride.

it does suffer from fuel level hiccups in corners. IDF's won't do that.

[plasticblack]

[/quote]it does suffer from fuel level hiccups in corners. IDF's won't do that.
[/quote]

Thanks for that info. I live in the Countryside and bends/corners are the norm...

I do have concerns over the age of the DCNF's but still want the look they give. I'd struggle to run to Webers at present and this is why I am looking at other options.

 

[bean]

a previous car had a 1776 motor with berg 42dcnf's - ran great idle to 7500rpm very smoothly.
i'd run them again for sure

[plasticblack]

Does anyone have any fuel consumption figures/info re: DCNF vs IDF? 

[bean]

apples and oranges comparison from me i'm afraid!

1641 with twin 40 idf's and i drove wherever i felt like it and didn't worry about fuel consumption.
1776 with twin 42 dcnf's, and a LOT more go - crime not to rev it really, and i used to get 20mpg on trips to work - luckily i only worked 10 miles from home.

one that made me  the most - the 1776.

if fuel consumption is an issue then a quick cal looker's probably not a good idea as a daily, more as a weekend warrior

[Fastbrit]

Used DCNFs a lot on everything from1600s to 2.1-litre motors while working at Autocavan, often with DDS manifolds. Great carbs although, as said, because they're were designed to be fitted to a Ferrari engine, with the throttle spindles across the car, they would flood on hard corners as the fuel overwhelmed the emulsion tubes. You used too be alb;e top get extended emulsion tubes for them (Berg, maybe?) which helped a little. Last time i fitted a pair was in 1983 on a couple of 1835 engines being used by a special effects company as wind generators! The Autocavan bay-window van had a 1600 fitted with dual DCNFs and it hauled ass - used it as the tow vehicle for the rallycross Beetle.

[plasticblack]

Used DCNFs a lot on everything from1600s to 2.1-litre motors while working at Autocavan, often with DDS manifolds. Great carbs although, as said, because they're were designed to be fitted to a Ferrari engine, with the throttle spindles across the car, they would flood on hard corners as the fuel overwhelmed the emulsion tubes. You used too be alb;e top get extended emulsion tubes for them (Berg, maybe?) which helped a little. Last time i fitted a pair was in 1983 on a couple of 1835 engines being used by a special effects company as wind generators! The Autocavan bay-window van had a 1600 fitted with dual DCNFs and it hauled ass - used it as the tow vehicle for the rallycross Beetle.

Welcome Sir..

I kinda knew that you'd have some info to share. 

I'm hearing lots of pluses and minuses for the DNCF's. Seems they really provide the power, but with some minor side effects along the way.

For me solid reliability is the main aim, so perhaps a set of 45 year old carbs is not such a good idea?

I'd love to go a different route with my project so I'll have to think things over carefully.

[Pedalpusher]

This will help on the cornering issue. I haven't have anything problem with my 42 DCNF's and I live in countryside too.

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Beautifully working motor across the rpm range, driving easy or hard.

-Mikko-

[Jim Ratto]

That's cool. Nice work!
A friend/customer of mine used to offroad race in the mid-late 1970's and came up with a "dry sump" float bowl for the DCNF's they ran to cure the issue. Never saw it in person.

[Zach Gomulka]

Sort of off topic but...
Who has used 40's and 42/44's? Supposedly the circuitry is far superior for a VW engine on the 42/44's. I used 42 Specials on my old type 3 and was very pleased with them but I've never played with the 40's. I never experienced fuel slosh problems either.

[Matt Tobias]

I thought Don Bullita used to run 44 DCNFs?

[Zach Gomulka]

I thought Don Bullita used to run 44 DCNFs?

He still does.

[Donny B.]

I run 44s on my 2165  and I ran 42s on my 1776.  I never had issues on twisty roads.  Where I had a problem was when I was accelerating hard from a dead stop and making a turn at the same time (like pulling out of a parking lot onto a main street).  What I believe happens is that the floats get pinned in that situation, one fully open and one fully closed.  This causes the engine to lose power.  Fuel starvation on one side and flooding on the other side.  Once it clears out everything is fine.  On my 1776 with the 42s I have gotten as high as 34 MPG.  I love them they are so smooth from idle all the way to wide open.