Jetting for 32/36 weber

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warrenrhen
Posts: 28
Joined: Fri Nov 13, 2020 10:09 pm
Your car is a: 1979 fiat 124 spider
Location: Apache Junction AZ

Jetting for 32/36 weber

Post by warrenrhen »

My rend just mailed me a weber 32/36 DFEV he had it on a IT race car but rthere are no main jets in it. What would be a good size to start with for my 2.0 whitch is stock except for headers and single plain manifold?
Cheers, Warren
79 124 spider
18 Dodge Charger R/T
20 Vespa 300 GTS HPE
Nut124
Posts: 748
Joined: Wed Oct 25, 2017 6:39 pm
Your car is a: 1978 124 Spider 1800

Re: Jetting for 32/36 weber

Post by Nut124 »

If it's been in a race car, you might want to remove and record all jets and venturi sizes.

Racetep.com has basic jetting for all Weber carbs.

https://www.racetep.com/webercarbjet.html

How close are the rest of the jet/vent sizes to the racetep list?
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Jetting for 32/36 weber

Post by 18Fiatsandcounting »

A good place to start with these types of Weber carbs on a Fiat engine is a 135 main jet and a 170 air corrector, and then go from there as necessary if there are flat spots, running too lean or rich, running at higher altitudes, etc. And I see that this is indeed about what the website pointed out by Nut124 suggests. (A good reference, by the way)

As for idle jets, that takes some experimentation, but basically you want the idle jet to be sized so that the engine runs the smoothest when the idle mixture screw is screwed out about 1.5 to 2 turns from seated (don't seat the screw too hard). If you have a flat spot in the transition from idle to main jet circuit, go up in idle jet size one or two steps.

As for emulsion tubes, that's way beyond my ability to assess what's best. Either use the table in the website, or use what came with the carb.

-Bryan
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