Carb jetting

[dinosabella]

Does anyone know where I can order new jets? I have a 34 ADF on a 1977 that was originally equipped with a 32. I run really rich and I have been told by a few different knowledgeable people that I need to change my jetting.

Thanks

[kilrwail]

http://www.weberjets.com/

How do you know you're running too rich? Without an air/fuel gauge it's hard to be precise. Running too lean can be catastrophic. What size are the current jets? Changing by one size - like 160 to 155 - results in 6% less fuel. Be careful not to go too small too quickly.

[Raze]

Both the Weber tuning manula and Artigue's Engine Maintenance and Modification manuals both talk about when you're over/under jetted. Weber says something about being less than 1 turn out on the idle mix screw means you may be too big on you jets, Artigue says all the way seated. Either way, if you're running rich and you're close to all the way in, you're too big. Artigue suggests going up +10 and retry, but you may want a +5 too just in case, it's easy to overshoot. Conversely if you're 3+ out on the Weber guide it says to go smaller, Artigue says 4-5+, again either way, too small is too small.

[dinosabella]

every so often the car starts to run like crap, i pull the plugs, and they are all black, I clean them up, put them back in and the car runs much better.

I never really tried tuning the carb myself, not really sure how to properly do that. A few different mechanics told me it's my jetting. So I'm sort of taking their word for it.

Is their a good resource for tuning a 34 adfh carb?

thanks

[majicwrench]

Don't mess with your jets. Figure out what is wrong, lots of things can cause black sooty plugs. You need a good carb mechanic.

[manoa matt]

The air/fuel mixture screw located at the base of the carb on the driver's side. IIRC it should be 1 1/2 turns out from fully seated. You can use the main jets and air correctors from your 32 ADFA. This will help you tune it: http://www.piercemanifolds.com/category_s/313.htm

In addition to the official Fiat spider factory service manual which covers some of the 32ADFA operation, Fiat published a workbook for the 32ADFA as a supplement that covers much more information and adjustments. I belive the 32 and 34 are so similar that some of the "on the bench" adjustments and specifications could be the same for the two carbs. Send me an email and I can send you the 32ADFA workbook.

matt.scarton@gmail.com

[majicwrench]

If, as you state, your problem is intermittent, it is certainly NOT your jets. Looks elsewhere.
Keith

[dinosabella]

Now that you guys mention it I don't think I ever properly set the carb, I installed it fresh out of the box from Pierce Manifolds years ago. I think a now retired mechanic adjusted it by ear real fast at one time but that's it.

I'm kinda confused as to what screw does what. Virtually all the brass screws that I can find on the carb are pretty inaccessible with the exception of one. My set up looks different from the pictures I have seen.

Later on today I will post some pictures and hopefully someone can tell me what is what.