I searched all over the place and could not find any decent adjustment procedures for the Nikki carb. If anyone has anything, please let me know. You would think the 320 service manual would have something.
I think I will just go by spark plug color, as mine is a little too white .
Which direction on the mixture screw makes for a richer mixture?
NIkki adjustment
Re: NIkki adjustment
mac, Let's see carb adj (inside to out) = Float level ,jets , metering rod (springs/depth) +vacumm/power pistons ,linkage -WOT +"idle stop" , accelerator pump -start/stroke/duration , Choke , finally Idle mixture screws.Gotta know if screws are a FUEL or AIR adj = most important! 
Are you talking mixture screws for Idle/off idle ONLY or are they in the power ckt. , like an external float adj (similar to holly) . I'm going with general SOP here , without taking apart , and if screws are for idle adj. - I don't believe externally your going to affect A/F much to show in plugs unless ,you can first "mess" with the power enrichment(rods ,piston,springs) from outside , or bigger factor is float level -and if that is an external adj. I mean also ,I don't know if you DID a full rebuild , but my point is pulling plugs to gauge things often - your (definately ) not dis-assembling carb, nor WANTING to every time! Although 40 years ago I had Mopar THERMOQUAD , so easy to work , take apart , adjust (maybe me?) , had the energy back then 
Keep in mind EVERYTHING comes "OFF" the float level , JETS next,then power enrichment(rods) , LASTLY idle screw adj. 
All that being (generally) in order of performance MAGNITUDE ,say. Remember - power enrichment generally leans out with steady cruise , then when you "mash" - on up to WOT it's ALL a function of Jet size (w/without rods) in conjunction with where your float is set.
Are you talking mixture screws for Idle/off idle ONLY or are they in the power ckt. , like an external float adj (similar to holly) . I'm going with general SOP here , without taking apart , and if screws are for idle adj. - I don't believe externally your going to affect A/F much to show in plugs unless ,you can first "mess" with the power enrichment(rods ,piston,springs) from outside , or bigger factor is float level -and if that is an external adj. I mean also ,I don't know if you DID a full rebuild , but my point is pulling plugs to gauge things often - your (definately ) not dis-assembling carb, nor WANTING to every time! Although 40 years ago I had Mopar THERMOQUAD , so easy to work , take apart , adjust (maybe me?) , had the energy back then Keep in mind EVERYTHING comes "OFF" the float level , JETS next,then power enrichment(rods) , LASTLY idle screw adj. All that being (generally) in order of performance MAGNITUDE ,say. Remember - power enrichment generally leans out with steady cruise , then when you "mash" - on up to WOT it's ALL a function of Jet size (w/without rods) in conjunction with where your float is set.-
Ted Heaton
- Posts: 41
- Joined: Wed Aug 13, 2014 9:32 pm
- Car: 64 Datsun 1500 Roadster
63 NL320 Sport truck
Re: NIkki adjustment
Turn the IDLE mixture screw in to lean. Out to rich.
This only effects the idle circuit.
Ted.
This only effects the idle circuit.
Ted.
Re: NIkki adjustment
My truck runs good, but when going downhill with engine braking, there is some popping through the exhaust. If I pull the choke out just a bit or give it a bit of throttle, it goes away. I will try turning the idle mixture screw CCW to see if that helps.