got my dual dcnfs...questions, linkage, spacers, jets, etc

I have seen these inlets too.
What‘s wrong with them?
They are 8mm, just like your fuel hose.
I would use them and not mess with drilling the carb.
 
Ulix said:
I have seen these inlets too.
What‘s wrong with them?
They are 8mm, just like your fuel hose.
I would use them and not mess with drilling the carb.
Click to expand...
Well, I just checked, and they are 6MM OD...I think I am correct in assuming these were made to be an uprade for a much smaller engine...I think my lawnmower has a bigger fuel inlet, lol. Of course I'm wondering if it will really make a difference? when I took off the filter cap, I can see there is a very small hole to allow fuel into the bowl, and a chain is only as strong as it's weakest link, so would improving flow to the filter section really matter? This does make me think of plumbing physics I learned when working with sprinkler systems- circuits usually start large and get smaller to increase fluid velocity to make up for pressure decrease
I dunno, a friend of mine says I should just use existing pump, and plumb it up, and see how she flies with existing inlet lines. I am pretty sure tho, that I can tap a 1/4" NPT thread into that casting that is a bung for the banjo fitting that everyone else has, and use a 1/4" npt elbow, into a 3/8" nipple....and use the existing inlet nipple for a fuel return. I still have the stock restrictor for the return line. of course I usually don't like using those pressed in fittings at all, as my first 28/32 weber had that just pop out one day, scary chit there)
But these seem very firm
 
I'm with Ullix, use the spigot that's on the carb. You should get a wide band air/fuel meter to set up the jetting and it will tell you if it's too small, you will start to run lean at high rpm even with proper jetting. You can always modify the inlet later.
 
Ugh 200 bucks for a wide band...yeah, really gonna need one
man you guys have no spirit of adventure, lol. That is scary drilling that, but that spigot is way puny, course my motor is not heavily modified either. Funny, Midwest has a pair of the same ones used, and somebody did exactly what I was thinking, but it is real hacky looking
 
I used to try and tune my dual Webers by use of the butt dyno but that only gets you so far. If you plan to play with carbs on a regular basis then that $200 is a worthwhile investment. There are plenty of guys running DCNFs who are happy to tell you what their jetting is but if their tuning specs are different and they also used a butt dyno then you approach proper jetting for your car but never lands on it. I borrowed a rig to tune the DCOEs on my X and I got close for every setting except for running way too rich off idle which was confirmed by fouling plugs after 10 minutes of driving. Without the meter I might never have figured out what was causing the misfire.

Having said all that, there was a long time in my life where $200 for a limited use tool was totally financially out of the question.
 
well taking everyones advice on buthchering, lol...in the meantime, I think I need to do some more research...was wondering if anyone knew about any free online documentation...was thinking about getting the haynes weber book

And yes Carl gonna find me a wide band...have thought about it for years, I think it is now going to be really necessary
 
on a side note. a lot of X1/9's went up in flames due to the press in fuel fittings (had it happen to mine but got lucky and an extinguisher was at hand) Most race car specs mandate they be removed and replaced with a thread in fitting. (very good idea)
 
Rod Midkiff said:
on a side note. a lot of X1/9's went up in flames due to the press in fuel fittings (had it happen to mine but got lucky and an extinguisher was at hand) Most race car specs mandate they be removed and replaced with a thread in fitting. (very good idea)
Click to expand...
that's what I was thinking...Altho these seem tight...My 34 Datr, they actually rotate in the bore, but I can't get them to come out, but don't leak...I notice on that particular carb, and these I just got, there is a little "ring" around where the fitting is pressed in....almost like they pressed or crimped in a little of the carb body around a barb on the fitting or something to prevent it from coming out
Anyways, I took the tops off the carbs yesterday and inspected them in some good light....the innards look good, but found some "not so good" stuff- 2 of the idle mixture needles were bent at the very tip (how da f**** do you do that?)...I ordered replacements, altho I know from experience the seats are probably damaged now. Also the two throttle plates on one, are slightly not centered, and look to be not seating correctly- Was gonna buy rebuild kits, but don't know float needle size, nor how to determine it. I will start another thread...joy
 
so where would I find this cool little bolt on arm?
1974 Fiat X19 Dual 40 DCNF Linkage Closeup - Cambox.jpg
 
hmmm...only thing I'm finding is this booger, wonder if the clamp bolt will clear the tappet cover...guess I can't lose for 13 bucks, and take the grinder to it, lol...really like the design of that arm on yours...maybe I should just weld up something...small piece of pipe, with a piece of metal sticking off of it, then tap a set screw hole
21jHt-6XFZL.jpg
 
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