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Im pretending to buy Twin Mikuni 40phh for my Datsun 1200 with A12 engine...


What you think? I need to modifiy my fuel pump? Change Jets? Which Dimensions?



The specifications that i saw on vendor

Mj 160 Aj 210 Pj 60 outer ventury 32 what does it mean?



Many thanks on advance




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Buy jets at redline.com I would strongly suggest you don't buy them unless you know how or are willing to learn how to tune them. They require a lot of patients to get set up correctly there are hundreds of thousands of jet/air bleed/E-tube/idle jet combos and may require a dyno and a 4 gas analyzer to get it perfect. Jetting is much easier if the carbs were in a kit for your engine in the first place so the E-tube will be properly selected then you just swap out jets till it is good.

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You CANNOT say what jets to use until you know which venturies you will be using. Venturi selection is the first step in tuning. 32 mm venturis are a bit large for an A12 so won't run perfect. For 6400 rpm I recommend 29mm venturis for excellent top-end power with good low speed response. Or for 6000 rpm use 27mm for stock A12 to get best response.


Or, bolt the Mikuni PHH40s on, adjust them, and see how it runs. It should run OK. Then you can begin tuning them to meet the needs of your engine.


For baseline jetting:

* 32mm venturi fit 128 main jets and 180 air jets

* 29mm venturi, 116 main jets, 165 air jets.

This will set the air/fuel ratio for cruising (non-accelerating mode)


Then comes the hard part - tuning for acceleration and low speed running. This is where each modified engine will be different: idle jets, power valves, emulsion tubes, accelerator pump adjustments, and possibly juggling the main/air jet combo (larger main + smaller air or vice-verse ).

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