Questions regarding the removal of 40DCNF carburetors??

The best advice I can give of is not to drop anything down inside them, or the manifolds after the carbs are off. Take your time. There are a couple nuts that are rather difficult to downright impossible to get to until you remove one of the adjacent carbs. Best to take a picture and make some notes so you remember which carb goes where, or (in case they mix them up), which set of linkages go where. Once you have the airhorns and airbox removed, remove the fuel lines (pull the fuel pump fuse in case you accidently turn the key on), disconnect all the throttle linkage (this is another "fun" job), and then start removing carb nuts and washers. A magnet is a handy tool to have nearby. Once they are off, put some duct tape over the manifolds to keep anything from dropping in.

You may want to consider redoing the coolant hoses in the engine valley under the carbs (while your in there).

As Pierce are the noted experts, I would imagine you could ask what they generally do with them, but I would believe they would come back like new.

 

Chris,

It is pretty straighforward, but watch out for all of the little parts that can fall into the engine or down the carbs. When you lift the air filter housing, there are pads under there with spacers. Those can fall out and down into the carbs. I put some clean shop towels into the carb throats to keep things from falling in, and I was glad that I did. Some of the nuts that hold the carbs to the top of the intake manifold can be buggers to get to also, but persistence pays off there.

I'd also suggest you take some pictures of how the carbs sit, how the various wires and pieces are attached. Then after you put them back together and reinstall them, do Birdman's carb balancing procedure. You car will thank you for it.

Cheers,
Steve

 

You grind down the nose of a long socket to get the trumpet hex nuts off, I think that's what Paul means...

And yea, of the 16 brass bushings that ride the studs in the base gaskets, at least one will already be lost so you need to spend two days worrying and looking for that......

Then you ha veto sync them when they return all shiny, an art in itself!

HTH.....

 

I second Paul's suggestion on changing the hoses in the valley and generally cleaning that whole area up while the carbs are out. It's the easiest time to do that work.

I had no problem removing the nuts that hold the trumpets, but I used a 1/4" drive socket and extension. They were small enough to fit in without any problems. Since they are not all that tight, you don't need a lot of effort to get them off. But, again, be very careful. And watch out for those brass bushings. When they go flying, they will make your heart stop.

 

There must be a patron saint of Ferrari carburetors, mustn't there be? I mean one to pray to in times like these? Good luck, Chris.

 

St. Venturi, Maybe?

 

That joke really sucks wind.

 

Hello Chris,

Just some general comments about rebuilding DCNFs. If one is rebuilding the carbs as a labor of love that is one thing, if on the other hand it is just to get them up to general specs, then that's an altogether different scenario. I know that the Pierce folks are the ones to go to. I would conjecture that the returned carbs would be like new. I don't know if they use the yellow zinc chromate [that I believe was OEM] or the more durable cadmium in their plating process. Either way, both are sacrificial metals, and they will deteriorate [some parts faster than others, don't know why though] over time. That is a bad thing.

Have Pierce rebuild them and then redo the fine points yourself as a possible option. You could always powder coat the re-plated parts and then reassemble. Powder coating in translucent gold over a polished bracket/bolt/washer literally gives you an impervious finish for life that looks like OEM. Powder coating is so cheap and easy! Polishing the aluminum truly makes it look awesome as well. Then you can always file and polish out casting seams on the intake to improve air flow...Pierce I guarantee will not do that for you. You could rebuild them yourself if you are looking to do it for the experience....key words here are research, faith, and patience. All of this may be irrelevant to your needs, however, I just had to throw in my two cents worth, OK maybe a nickels worth then.


Take many, many pictures, and download all of Pierce's PDFs on the 40s just to get acquainted with the parts. My rebuild kit had the wrong jets in it. I would check what is originally in your carbs. If things were running well then make sure your idle jets and main jets remain the same size on the rebuild. I kept my original fuel filter as the new one was plastic junk IMHO.


If this business interests you check out Russ's thread about the 44 DCNFs float setting in this technical section.....lots of amazing info. that Russ and his fellow DCNF gurus have put together.

Ciao,
George

 

Very good advice. Seriously, carbs are actually very simple, and not hard at all to disassemble and clean. But obviously if you dont feel confident or dont have the time, an expert isnt a bad idea. Just out of curiosity what does Peirce get to overhaul four of these carbs? And do they drill out the lead plugs?

 

If you are expecting to get them back ready to bolt on make sure that Pierce understands that. My 36DCL's came back needing total adjustment before they could be tuned. Throttle plates not closing, bottoms not flat, etc. But the price was really right.

 

what's often overlooked is; make sure, that the shop who rebuild the carburettor - is aware of those myriads of lead plugs... if they don't drill them out anyway, like Paul stated. Most carbs are damp and this is mostly caused by those leaking plugs and not by any gaskets.
Ultrasonic cleaning makes things worse - and it is mandatory to restake the plugs while rebuilding the carbs.
There's either a Weber special tool for performing this, but also a simple alternative method. But I know the disappointment when seeing freshly rebuild, nice clean carburettors, maybe with freshly plated hardware, leaking like hell, just because noone thought about those plugs.

Best Regards from Germany

Martin

 

Buy the Haynes Weber book.

 

I got four 40 DCNF-12 new from GT Auto Parts in Az for a very attractive price. Worked terrific.

 

Hi Chris,
My carbs are 44 DCNFs [close enough]. They had approx 20 K on them when I started the rebuild [work still in progress]. I've had a lot of discussion about those plugs. None of my plugs were leaking, so I'm leaving mine be.

As stated before, it's not hard to bring them to pristine condition, as well as doing it better yourself when compared to a shop doing it for you.

Basically, the following items should be either plated/powder coated or for the DIYs polished/powder coated: bolts, washers, screws, springs, and all levers. That should be about 20 items per carb IIRC. Since mine were 28 years old, but with low miles it was easy to see what was originally plated.

FWIW here are some pictures of a 44 DCNF. I'm still not finished with this one, will post a completed carb soon, but you get the general idea.

Ciao,
George
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