Carb Swap 32 ADFA2 to 32 / 36 DFEV

[jon8christine]

My 76 spider currently has a 32 ADFA2 carb and as part of my performance upgrades I'm swapping out to a 32 / 36 DFEV from Allisons. I've pulled the old 32 ADFA carb off and the eight hoses that came with it including:

- In and out for coolant choke - not needed with the electric choke (just plug / cap these hoses/fittings or remove fittings if threaded and plug? what's best?)
- To the top of the charcoal vapor canister
- To the round air filter housing (in addition to the large crankcase breather hose)
- Fuel return
- Fuel in
- To the middle of the charcoal vapor canister
- To the front of the electrovalve

Open in new tab as seen here

https://drive.google.com/file/d/1ZEGfo1 ... sp=sharing

Now I need some help installing the new 32 / 36 DFEV, which came with no diagram labeling what the THREE hose connections are for please. From my research I've guessed in the link, but would like some verification and some help on what actually gets connected to the single vacuum port and what to do with the other hoses namely the electrovalve, vapor canister top, canister middle and air filter housing? Thanks!

[18Fiatsandcounting]

Just a guess on my part, but here's where I would start:

Coolant choke: Yes, you can cap off the two hoses, or simply run a direct hose between the two connections points, which I believe are a nipple on the heater hose that runs under the exhaust manifold and a similar nipple on the rear end of the intake manifold.

Top of the charcoal canister: This is for capturing vapors from your carburetor bowl, so I believe one of the top connections on your DFEV is for this.

Round air filter housing (the smaller 1/4" or so tube): This is no longer used on the DFEV.

Fuel return: I can't tell for sure, but your DFEV may not have a connection for this. In older cards, there are two brass inlets into the carb float cover, near the 3/4" or so brass nut that holds the filter on the carb cover. The smaller is for the fuel return, and the larger is for the fuel inlet. I can't tell from your picture of your DFEV, but you may not have a fuel return. You may need to remove the carb float cover for your new DFEV to see what is actually going on with the brass inlets.

Fuel inlet: Again, not totally sure, but the brass connection you label as "Fuel return" looks to me like the fuel inlet. See above on removing the float cover to verify.

Middle of the charcoal canister: It's likely there is no corresponding port on the DFEV, so you might need to cap it off.

Front of the electrovalve: This is a feature not present on the DFEV if I recall. Cap it off.

On your picture of the DFEV where you label "Vacuum for ??", my guess is that this is the vacuum port for the distributor vacuum advance. I don't know if your distributor has this, so you might need to cap off if it doesn't.

Overall, the DFEV was meant to fit a variety of engines (not just Fiat spiders), and so some experimentation may be necessary to get it all straightened out.

Hope this helps.

-Bryan

[jon8christine]

Thanks for your thoughts, I'm diving into it tonight so maybe I'll start by dissecting the carb.

[geospider]

Agreed with Bryan. I have done this conversion on my '79. so a few different connections.

My 32/36 does not have that larger brass fitting you list as inlet. the other is the inlet and on mine; there is no return from the carb. Therefore I use a 3 port fuel filter with the return line: lot so people make these. I am curious what that other brass line is for. You will want to take off the top to check and rest the float setting anyway, so you can take a look at that fitting.

My charcoal canister attaches to the intake manifold. I do believe there is one that is blocked that I do attach to the old 28/32 for 1 day every 2 years for smog (oh joy). I tend to forget the details until that ugly day.

no gulp valve

crankcase hose to new air cleaner, there is a fitting but you need to mess around the the size of the hoses and fittings.


geo

[jon8christine]

Pulled the carb top (first time) and you're right, the smaller fitting that I thought was for the return is the fuel inlet to the bowl. The larger fitting on top looks like it travels in to the main venturi tube, but may also be a bowl vapor port, hard to tell. Mark said it hooks up to the middle of the vapor canister, so that's where it is hooked up for now. I put a tee on the single vacuum port on the bottom and ran one leg to the top of the vapor canister and one leg to my little crankcase breather also per Mark.

Now my only problem is getting it to run. So far it won't start, but it's late so I'll have to troubleshoot tomorrow.

[18Fiatsandcounting]

I'm not really sure what that larger fitting does, as most of the DFEVs that I've seen have the metal boss on the top cover, but the hole is not drilled and there's no brass fitting. Some sort of emissions thing? Also, if your charcoal canister is like the one in my '71, there are 3 fittings to it: 1) at the bottom, a line that goes all the way back to the gas tank, 2) an angled fitting in the middle that goes to the float bowl (to capture vapors), and 3) a smaller fitting at the top that connects to a vacuum port somewhere on the intake manifold.

Every Fiat I've seen seems to have a slightly different emissions setup depending on model year...

As for not starting, I'm assuming it cranks fine but just won't fire? The first thing to check is to work the throttle while staring down into the two venturis with a flashlight. You should see fuel squirting out of at least one of the accelerator pump jets on the edge of the barrel and pointing towards the middle. If there's no squirt, it's likely that you're not getting fuel to the carb.

-Bryan

[geospider]

Agree with Bryan...again.

I have had a few 32/36 and never had that larger brass fitting.
the vacuum port near the idle mix screw: that's for vac advance on your distributor. I would cap it if you don't have that advance on your year.
the Crankcase vent should go up to the air cleaner and there is a fitting on lost for it. you will need to reduce the size of the hose to this fitting, but you don't want to reduce too much. attaching to that little port I am guessing not great for the vent. I have read differences in this on here.
Also, the canister vac line would normally come from the intake manifold. you can use a T fitting: one for the brake booster and one for the canister.

you will also need 12V lead for the elac choke

Staring: follow Bryan's advice. Assuming you made no other changes but carrb, you just need gas.

[jon8christine]

Thanks for the advice. I'll have to redo a little replumbing, but none of that should be keeping the engine from running should it?

I checked for fuel at the carb by opening the butterfly's and then 'flooring it'. Nice little squirt of gas. I haven't pulled the plugs in years so decided to check them, though it was running before I swapped the carb. They were dirty but fine. Still wouldn't start by the usual method of ignition on, hit the gas once and then turn the key. Tried giving it a little constant throttle and it reluctantly started up. I have the idle screw at the recommended 1.5 turns out, but had to turn it another turn in to keep it idling. Do I need to rejet it for my 6200 ft elevation?

My other question now is what is the other adjustment screw behind the electric choke? These instructions suck and Google isn't much better! It sesems to act the same as the idle speed screw.

[18Fiatsandcounting]

Geo and I are going to tag-team our answers here! Let's first get that bad boy running. Don't expect a carbureted Fiat to start like a modern car. Sometimes you have to press the gas pedal repeatedly (to squirt fuel into the intake), and sometimes you really need that choke to be working. Sometimes you hold the gas pedal to the floor while cranking; sometimes you leave it alone. Each Fiat is different. You'll learn what works to get it running. I could make a sexist joke here, but I won't.

So, pump the gas, crank the engine, make sure the choke is working, and get it running. After it warms up (20 minutes), we'll start to diagnose what could be wrong.

-Bryan

[davidbruce]

That is the mixture screw. I remember it being a pain to get at but I had 1 particular screwdriver that worked. When I installed my 3236 I removed the top to find some brass and other debris from the manufacturing process. I also found the float level too high. I used the attached to set it up and found I had to screw in the idle enough to make it run well, adjust the mixture which resulted in a higher idle. Turn the idle down and reset the mixture. I did this several times and then adjusted the timing to best idle and maximum vacuum. I then repeated the carb adjustment and was very happy with the results. It started right away but always smelled a tad rich to me. According to the settings i had the idle jet sizes were correct. I contemplated a hotter plug but the color of the stock ones was about right. This was on a 2 litre with the stock electronic ignition and I live at sea level.

http://www.redlineweber.com/html/Tech/c ... _best_.htm

[jon8christine]

Thanks for the iterative process description. I've got that manual, trying to follow it. I checked the float when I pulled the top and it's right at the 18mm that Weber redline suggests below the gasket before it depressed the ball and spring.The screw I'm talking about is up higher behind the choke here

https://drive.google.com/file/d/1R2jK4J ... p=drivesdk

Looks like a choke adjustment, but it also contacts the linkage that is connected to the idle speed screw here

https://drive.google.com/file/d/1RKHZtj ... p=drivesdk

So it affects the idle speed screw. Where is this choke screw supposed to be set when setting the 1.5 turns on the idle speed screw then working on the mixture screw in the carb base below the choke screw here

https://drive.google.com/file/d/1RALIUi ... p=drivesdk

[geospider]

the screw behind the choke is the fast idle set. honestly, I left this alone and my fast idle has been fine about 1800, then kicks down to 900ish; these tachs tend to bounce down there.

the mixture screw is below the Vac fitting that you have have plugged if no vac advance on dizzy.

at your elevation, I would think you could get it going fine, then fine tune with jetting but dont get caught up in that at this point.

i would start with mix screw out 1 1/2 and the idle set in a bit to get it warm, then start setting you best idle. I think Pierce Manifolds has a good process for set up, at least to start.

[jon8christine]

Spent the last hour playing with it and that worked for me David. Set the fast idle screw so it rested on the linkage (had already messed with it so curious where others have it set, but don't think it matters too much as long as the choke engaged correctly as after the choke is warm the linkage rotates and the screw is no longer in contact with anything). Then turned in 2.5 turns on the idle speed screw to keep it idling and get it warm. After the choke was fully open and it was warm I started turning in the mixture screw and ended up setting it at only a half turn out from fully closed by ear. At that point it was running much faster so I could turn the idle speed screw back to the 1.5 turns in and have an idle about 7-800. Played with the mixture screw again and ended up with a best lean idle at 3/4 of a turn out. RedlineWeber says if the mixture screw is in that far that means the idle jet is too rich (large), but it's running better than it ever has since I've owned it. Very responsive. I'm doing brakes at the same time so haven't driven it yet. Still have the vacuum port teed and setup how Mark suggested.

The distributor says Bobina on it but looks like the Marelli from a 1608 engine in my Haynes manual, but does not have a vacuum line to it. Need to do some research on timing it now I guess.

https://drive.google.com/file/d/1RPu9iH ... p=drivesdk

[davidbruce]

HI Jon, my understanding is you want the idle screw in as far as possible. 1-1/2-2 turns is max. I'm not surprised at your altitude that it comes across as rich. Glad it worked out. I was unable to open those pics but it sounds like you are on the right track.

[18Fiatsandcounting]

I couldn't open the pictures either (don't have permission), but no matter, I agree that your idle mixture screw would need to be turned in farther since you're at 6200 feet (or see below). Normally, the Weber carbs on Fiats are fine up to 3000 or 4000 feet, but once you get beyond that, you'll need to lean it out a bit. By 10,000 or 11,000 feet without adjustment, the engine may still run but it will be down significantly in power. That's about the highest mountain road I've ever done on my spider, and while it made it, I think I was down to second gear on not much of an incline.

You can either lean out the idle by turning in the mixture screw as you've done, or going one or two steps down in idle jet size. Idle jets are usually a 45, 50, 55, or 60, so if you have a 60 jet in yours, you may need to drop down to a 55 or possibly even a 50. The markings are on the part of the jet that sticks into the carb, and they can be very hard to read, but they are there.

-Bryan