DFEV on 1608 - what jetting works for you

[chrisg]

I've just finished putting a 32/36 DFEV & single plane '74 intake manifold on my otherwise stock '71/1608 124 Spider. Finding nothing really firm as far as reports of success from similar setups, I just used the jetting it came with as a starting point. Anyone here got a report on what jetting they found successful on similar setups? Thanks in advance,-c

[mbouse]

huh, i was just getting ready to cry "unkle" myself for a 32/36 DFEV for a 1755 engine.

i have idling trouble, and can't shake it.

Have you asked Brad Artigue?

[chrisg]

Thanks....I just got a little feedback. Mine idles great..or, so it seems, but wants to die like sudden starvation coming off full throttle & feels like it's just not breathing enough with both barrels opened. I'm not home right now, but I think it's running 37/40 mains, 60/50 idles & 160/165 air correctors (main/2ndary, respectively....and i forget which emulsion tubes). That was a VW setup & I believe I would expect idles to go down & mains+airs to go up.....I have a 34DMSA on another 1608, but that engine is currently hanging out in a friend's car (long story), so I haven't checked what I was running there (which, was not necessarily ideal, but does run well at all throttle positions & transitions). So, I was just looking around for notes to compare to. In my case, I was fortunate to be starting with a virgin (albeit, setup for a VW) carburetor to start working with, so I can rule out all the usual wear-related problems I'm used to considering.

[chrisg]

huh, i was just getting ready to cry "unkle" myself for a 32/36 DFEV for a 1755 engine.

i have idling trouble, and can't shake it.

Have you asked Brad Artigue?

what kind of jetting are you running?


btw, every time i see your 'michigan short shifter' sig, i think of my "east TN hillbilly short shifter" that I made years ago....not that there's any comparison other than just being 'short'...lol

[mbouse]

full stock new carb...whatever those jets are, and a stock intake with a stock head.

it is a '78, and i cannot get it to idle. barely get it to run when the choke is closed and the engine is cold. after it warms up, it will idle at 1500 rpm. if i drop the idle speed then, i will not get it to run the next time i fire up a cold engine. i've cranked the mixture screw all the way in, and that seems to help very little.

then.... if i pull a medium size cap off the intake manifold (ex-port for a emissions hookup) the engine will race like crazy.

so, i am presuming i have too big of an idle jet. just haven't found the time to begin the research.

[bradartigue]

Stock setup DFEV is probably too big for a 1608. Everything described in this thread speaks to jets that are too big, especially the main idle jet.

Stock -> http://www.artigue.com/fiat/Carbs/CARBU ... 20DFEV.pdf

Idle Main - 60 Idle Secondary - 50
Main Main - 137 Main Secondary - 140
Main Main Air - 165 Main Secondary Air - 160
Pump Jet 55

Which is about what you need for a 3.2 L V6.

For starters just swap the idle jets. 50 main is probably still too big, and a 60 secondary is likely way too big, but you should be able to get it to idle with the idle jet mixture screw and just 1-3 turns on the throttle stop screw. When setting idle the goal is to rely on the mixture screw as much as you can (for example my car idles on the mixture screw alone at around 400 RPM then the idle stop screw brings it up to 850).

I would suggest a 45 idle main and leave the 50 secondary. If you have hesitation with this setup go up (55) or down (45) on the secondary. Once you get that sorted out (since a 45 will work I'm quite sure, at worst a 50) if you are still running rich, as in black smoke and crud on plugs, go down on the main jets - 130 & 135. The other jetting should be fine (airs and pump).

Tuning instructions are in this:

http://www.artigue.com/fiat/Pubs/Artigu ... 124_MM.pdf

[chrisg]

that all sounds right. Brad - did you end up trying/using different emulsion tubes? I was hoping someone had just done this & written down what they ended up using so I could use the same as a starting point. Whatever is the optimal jetting, I was (and still am) certain that the out-of-the-box jetting was not it!

[bradartigue]

You shouldn't need to change the emulsion tubes.

The jetting I sent you should do it, but with any motor you have to fine tune it yourself. Stock jetting is too rich for the smaller motors. It's OK for the 2000 in my experience.