I have a datsun 1200 gx coupe with a a14 head, had some problems with the standard hitachi downdraught carb, so i removed it and installed twin dellorto 40mm carbs on a well ported manifold wit the rubber fittings between the carb and manifold, it's got 58 idling jets, 7772.8 emultion tubes, 210air, 130mains and 32mm chokes. it's revs up fine but cant seem to get it to idle on all the carbs, if i pull off the cyl 3&4 plug wire it idles exatly the same, which tells me it's not idling on the back carb. it's got original (in very good condition) links between the 2 carbs. it's not spitting back and revs up perfectly but no idle

i have everything else same but 60 or 65 idle with standard cam, what do your plugs look like?

Hi mate,

I had the exact same problem yesterday, and I had to pull the carbs off to figure out the problem.

You have to adjust the linkage between the two carbs so the butterflys are open equal amounts at all revs. The rod that runs through the carbs can bend over time, meaning that one carb can be slightly off. I shone a torch through the carb as if throttle was on idle, and adjusted the linkage so that the amount of light shining through past the butterflys was equal on all carbs. There may be other wasy of doing it, but it solved my problem.

Hope this helps.

that's where you need a balance gauge, or if your up to it,
some 5/8 heater hose, rest it just in the mouth of each throat,the other end to your ear.. and set them up so the hissing noise is equal,

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I've replaced the plug leads, plugs (ngk bp6es) new coil (still using the resitor) got a new dizzy today with new rotor, points & condensor. will see if that helps, otherwise i'll drill out a set of idle jets to 60 and try otherwise 65. will keeps you posted. thanks in advance

Had a air leak on the front of tha manifold... will see how it goes today, battery went flat from all the struggling. does ram tubes help with idling or top end?

The longer the runer the lower the optimum rev range, so it should help it idle. allthough the difference would be hardly noticeable at idle I would think?