Stock 79 Spider 2000 carb rebuild time

[racydave]

When you buy a used carb, youre takin a chance, esp thru e-bay. there is something to buying a new carb, and having the correct jets,etc... and a gaurantee from a reputible vendor. Unless youre a good carb rebuilder... Also there are alot of good vendors not yet mentioned, including Mark.

[bradartigue]

Hello,

I wrote a bunch of stuff on this topic. You can download the document at http://www.artigue.com/fiat

I would recommend buying the 34 ADF as a direct replacement; you'll also need an 1800 manifold to make it really sing. 32 ADFA isn't a bad replacement but is not as big or wonderful.

This is one area you will want to talk to a real FIAT vendor or Weber reseller. On your car you need the vacuum port in the manifold base to run the distributor advance. Otherwise you're robbing yourself of low end power. Discuss this and the correct linkage with them.

By the way your stock exhaust is very restrictive, you might want to consider using one from a later (FI) Spider 2000 or a Spider 1800 with a 4-2-1 routing.

These three things (carb, intake, and exhaust manifolds) will improve the perfomance of your car so much you won't recognize it.

[Hvnfn]

Too funny, I was just reading a doc on carbs from your mentioned site! It is a good piece of reading!

[mbouse]

Thanks, Brad for the reminder. We've discussed everything you listed EXCEPT which is the "best" carb for this application. I have a feeling we aren't done discussing some of the detailed how-to steps in between either.

your input is appreciated.

[bradartigue]

The previous edition of my modifications "book" (after 90 pages I decided to call it a book rather than a guide..) I was arrogant enough to recommend a "best" carb rather than what I'm trying to do now which is the "right" carb. And it's not always easy - but fortunately the availability of carburetors makes the choices fairly limited.

Downside of the stock 2l is the head, exhaust, and carburetor. It cannot breathe. Just installing a larger carb helps a ton, but really open it with a stock 2l FI head or an 1800 head with the air pump stuff plugged. And a 4-2-1 exhaust or buy a header. These things can be had pretty cheap and make all of the difference in the world.

I also can't stress enough - buy a NEW carburetor or an expertly rebuilt one. Old carburetors can cause you no end of misery since the problems are almost always in the shaft bushings - and replacing them and rebuilding almost costs that of a good new Weber.

I have run all of these at various times, and on a variety of block/head combos:

Weber ADHA - stock 79/80 Carburetor. A pig. Unless you live in California you are likely wasting time and money trying to get this thing to work correctly. This entire carburetor is centered around some ridiculous emissions control regulations that had no business on a small 4 cylinder engine. A properly tuned FIAT DOHC with one of the other carbs and without all of that regulatory crap will pass emissions every time.

Weber 32 ADF - stock 1978 Carburetor. A direct replacement for the ADHA and, really, you can get a spacer and run it on that 79/80 manifold. Ideally you should get the 78 manifold (or earlier since they interchange). You will get a performance increase either way and it is much easier to tune and repair. Port it for the vacuum or it might have it already (some do). Passes emissions in GA and probably other states except California.

Weber 34 ADF - varooooooooom. On an 1800 manifold, varoooooooooooooooom. Make sure to get it vacuum ported or buy it with the port. This was pretty much the standard upgrade carb sold by every vendor throughout the 80's and 90's and, I think, even today. Worth every penny and (technically) a more sophisticated animal than the DFEV/DHS/DMS/etc "D" series carbs. Passes emissions in GA and probably other states except California.

Weber 32/36 DFEV - like a 34 ADF but a little more fuel efficient on the city side. This is the modern equivalent to the Weber DMS and DHS carburetor and has an electric choke. A little more work to get it installed but it is very nice...and smaller under the hood, it doesn't have the ADF throttle body. Still produced new and has the vacuum porting. Passes emissions in GA and probably other states except California.

Weber 36 ADL. What can I say - I ran this carb on an 1800 head/2000 block with stock pistons and cams and produced enough power to blow my u-joints out. They weren't new U-joint but it sounds better to say it the way I did. Has the vacuum port, hellatiously big barrels. There is also a 38mm if you have the compression and cams for it. I passed emissions in GA with this hog. I also hooked the fuel return circuit up wrong and sucked the gas tank inwards, which is another story altogether. Same otherwise as a 34 ADF series.

Weber dual 40 IDF. I think this is a lousy choice on a stock 2 liter. With an 1800 head it is slightly better but you'll never pass emissions. You really need a compression boost and cams unless you just want to tinker with the jetting for months. You won't find me recommending IDFs to anyone, ever. I've never seen where they outperform one of the big single carburetors - but I'm a long way from seeing every possible engine combo anyway. Frankly some people love them.

Fuel injection - you can fit an entire Bosch L-Jet from a Spider 2000 on any of the Spiders if it fits under the hood. A lot of work but is the best fuel delivery of the bunch. L-Jet with a compression boost is fantastic (it really kicks with 9.1:1 pistons on the otherwise stock 2 liter). Passes emissions in GA and probably other states except California (unless FI was stock on the car then it passes CA as well).

Hope it helps

Brad

[Danno]

let me be the third or fourth or whatever to say that getting a rebuilt carb isn't necessarily good. Like Brad just mentioned it should be rebuilt by either someone who is very good, or by yourself (it's one thing to screw something up yourself, and find out what went wrong, it's a completely other thing to know that some other guy screwed it up, but you can't figure out what;s wrong!)

I should take this time to say that my carb wasn't rebuilt by "some dude" it was expertly rebuilt by none other than Jon Logan. You'd be better off buying one used and sending it to Jon (or some other "expert") to have it rebuilt, than to buy one that you THINK is rebuilt right. In fact, why don't you just shoot Jon an email and ask him if he has one? there's a good chance he does.

[racydave]

Brad, if you have any documentation related to my 36 ADL, id be very interested... Thanks, your old article led me to it!

[mbouse]

Weber 32/36 DFEV - like a 34 ADF but a little more fuel efficient on the city side. This is the modern equivalent to the Weber DMS and DHS carburetor and has an electric choke. A little more work to get it installed but it is very nice...and smaller under the hood, it doesn't have the ADF throttle body. Still produced new and has the vacuum porting. Passes emissions in GA and probably other states except California.

i love my 32/36 because it gives me the boost i read that the guys using the 34 are getting. and, checking my fuel economy (which i seldom do) i get 25-26 mpg. for a city drive to 60 max mph this is really nice. lots of zip, and easy to install on the 79-80. Dizzy hooks right up, and so does the fuel intake. no guess, no gosh. lots of plastic pipes disappear too. the shorter size also allows for a 2" Performance air breather, which looks impressive and sounds real masculine.

the extra time involved to switch to the electric choke is in how you decide to block off the water ports for the old water choke. finding a source for 12 volts is easy....since you are discarding the idle solenoid.

I cannot wait to get my 1800 intake rebuilt and installed.

Already have done the 4-2-1 on the other side. those items are starting to run a little scarce...so if you are planning this project I would suggest hunting for this set up right away.

[bradartigue]

Brad, if you have any documentation related to my 36 ADL, id be very interested... Thanks, your old article led me to it!

Here is a ton of information on the carbs:

http://www.mirafiori.com/faq/content/we ... 38_adl.htm

[Hvnfn]

There is a guy here in town selling an engine with EFI out of his '81 Spider for $350... tempting...

[mbouse]

yours would not be the first to be converted in this manner.

[Hvnfn]

Too much fun as of late...

The K-519 kit with the 34ADF carb is no longer in production and is NOT NOT NOT cheap to get my hands on! The minimum was $450!! Ouch!

[mbouse]

go with the 32/36 DFEV and be done with it!

I promise you will not be unhappy.

[Hvnfn]

Doin the 32/36 DFEV, I dont know why the guy at Weber said I needed an adapter... it should be a direct bolt-on. What kind of modification did you need to do to the linkage, if any? I will order one of these carbs tomorrow.

[Hvnfn]

before I do the intake/carb conversion I want to get the car to a running known good state. So...

I tightened down those 13mm bolts on the carb and behold.. she idles fine again... had to have been a vacuum leak at the base gasket. I sprayed carb cleaner around the base when she is running and it doesnt advance. Good.

Now, for almost as long as I have had this car, in order to start the car when cold, I have to pump the pedal for almost 15-30 seconds before she starts... it is hell on the battery. Once started, if I kill it, she fires right up no problems... Before firing the car up in the morning, the fuel filter is empty, which I would expect being that the tank/lines are not pressurized... but shouldnt the bowl have enough fuel in it from the day before to start the car and allow the fuel pump to begin filling the bowl again? Is it possible fuel is seeping from the bowl overnight? I just cant think of where it would seep to, unless there is a really slow leak at the drain? And I am assuming that there is a bowl drain. Should I even concern myself with this given that the carb and intake are being replaced VERY shortly?

I am curious about the operation of the fuel pump... Does anyone know what the spec pressure is from the pump? How can I go about testing that the pump is working at optimal? Inline filter with a pressure guage available or something?

What is your opinion on replacing the mechanical fuel pump with an electric fuel pump? Is it something to add to my replacement list?