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Nissan 720 Passing Emmisions


TheProtoSmith

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I should have been more specific, it runs and sounds fine, but there is like very little power. Atleast at low rpm, high rpm feels comparable to both coils firing

There is also the chance that I have the car too far leaned out and it is just low in power.

 

Edited by TheProtoSmith
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Smooth but non linear Torque curve. Rises steady, until 80% throttle after that throttle input does nothing. Sounds like too lean to me but I'm definitely learning a lot about these Nissan 4 bangers. Is jetting the only way to tune air mix for non idle conditions.... Seems a bit coarse to really dial in a machine

Edited by TheProtoSmith
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24 minutes ago, TheProtoSmith said:

 Is jetting the only way to tune air mix for non idle conditions.... Seems a bit coarse to really dial in a machine

 

Yes but remember the carburetor is a totally mechanical device that mixes gas with air using only the air being sucked into the running engine for power.  It hasn't changed in over 120? years. EFI on the other hand uses sensors and a computer to precisely calibrate the perfect mixture and fuel under pressure is injected not using the engine at all.

 

Only recently have wide band O2 sensors been cheap enough for anyone to have them. They will tell you at a glance what the air fuel ratio is. Before this there was the art of 'reading' the spark plugs to know what was going on.

 

 

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3 minutes ago, TheProtoSmith said:

So rebuild carb? Or is it there a way to just blow out the secondary.  That jet was sheared when I replaced them

 

You changed out the secondary jet? What number was on it... what number did you replace it with?

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17 hours ago, TheProtoSmith said:

Alright old jets are out one was cracked, both were too big. Like #200 ish mix screw now makes a difference wooo. Did a 92 and 97 on the new jets.  Now I gotta tune this carb in. Runs pretty well when both coils are on and like ass when you full throttle. Which should mean the system it too far retarded right?

(Because of the full throttle second coil shut off circuit?(

 

Maybe I installed backwards?

 

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