Weber DCNF 40 Carb

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124racerinIA
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Location: Iowa

Weber DCNF 40 Carb

Post by 124racerinIA » Mon Mar 21, 2011 2:26 am

Hi,
Does anyone have specs. or pics. of an adapter to match a DCNF to a standard Fiat TC manifold? I've heard that this is an improvement over the 34DMSA carb I'm using now. The engine is a slightly modified 1756. The current intake manifold does not have a provision for heated water from the engine. I've also installed Alquati 24/1 cams, gasket matched the intake, and a header with free flowing exhaust.
Thanks,
Jon

Guy Croft
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Re: Weber DCNF 40 Carb

Post by Guy Croft » Mon Mar 21, 2011 9:55 am

no and for good reason, the DCNF is for transverse units. It's to to with the float chamber orientation.

FWIW (in stating that) I am frequently told, 'well I run IDFs transverse and they work oK,' or 'I use DCNF on a RWD setup and they work OK.'

And when I ask if they ever suffer fuel starvation they say, ' yes but it isn't too bad.'

So be it, what can I tell them??!!

G

124racerinIA
Posts: 7
Joined: Wed Jan 26, 2011 3:27 pm
Location: Iowa

Re: Weber DCNF 40 Carb

Post by 124racerinIA » Mon Mar 21, 2011 12:59 pm

Thanks for checking in Guy, I've heard of an adapter that turns the carb 90 deg. That is why I came here to get good advice.

Jon

engineerted
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Re: Weber DCNF 40 Carb

Post by engineerted » Mon Mar 21, 2011 1:11 pm

Jon,

I will email you Jim Scurria contact info, He ran this setup as well as I. I don't like the adapeter I have it is too thin and dosn't seal well.

Ted
74FP SCCA 124 spider

vandor
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Re: Weber DCNF 40 Carb

Post by vandor » Fri Apr 29, 2011 4:23 am

Hi,

>no and for good reason, the DCNF is for transverse units. It's to to with the float chamber orientation.

I think he wants to use it as a single carb on a 124, so it would be oriented the correct way, East-West :-)

The adapter can be a simple piece of aluminum, about 10-15mm thick, with 2 sets of holes drilled, one to bolt it on the
manifold, and one for the carb.
bye,

Csaba
Auto Ricambi, LLC
GC book #288

124racerinIA
Posts: 7
Joined: Wed Jan 26, 2011 3:27 pm
Location: Iowa

Re: Weber DCNF 40 Carb

Post by 124racerinIA » Sun May 01, 2011 7:57 pm

Csaba,
Thanks for checking in. I have e-mailed Jim and mounted the carb. I'm currently trying to work out a stumble off idle. Any thoughts?

Jon

vandor
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Re: Weber DCNF 40 Carb

Post by vandor » Tue May 10, 2011 6:40 am

Jon,

I has been a long time since I tuned a DCNF, but I would look at the accelerator pump sizing. That, and the idle jet.
bye,

Csaba
GC book #288

124racerinIA
Posts: 7
Joined: Wed Jan 26, 2011 3:27 pm
Location: Iowa

Re: Weber DCNF 40 Carb

Post by 124racerinIA » Sat May 21, 2011 6:58 pm

Csaba,

I've gotten the idle jet sizing worked out by using Pat Braden’s method. I currently have 45 jets in the carb. I tried 40's in it and that made it way too lean.

I'm going to try a 45 accelerator pump jet next to see if I can prolong the pump shot. I looked into the carb as I accelerated it by hand, and I feel like the fuel was not transitioning from the idle circuit through the pump shot into the main circuit smoothly.
I also feel like the main circuit is not vaporizing the fuel enough, so my next step is to increase the size of the air correction jets. It now has 180 airs in it. I'll go up to 200 next etc.

Let me know what you think and if any of my logic is flawed.

Thanks,

Jon

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