* Smoke Setscrew *

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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* Smoke Setscrew *


Post by philip »

The smoke setscrew is used to properly position the Fuel Control Lever in the RUN position. This setscrew is safety wired at the factory but over time, miles, changes in fuel quality, alititude, or new injectors, this RUN position may well need optimizing (see the Altitude Compensator thead). Visible smoke in the rear view mirror under hard acceleration is a clue.

The "smoke setscrew" on the Diesel Kiki inline pump is roughly equivalent to the adjustable main jet on an old lawnmower. Push it to the left (lean), the engine dies. Allow it to spring to the center position (ideal), the engine runs. PUSHING it harder to the right (rich)(against the "excessive fuel stroke" spring), has the effect of an idle enrichment circuit (not quite a choke).

Turning the setscrew clockwise will LEAN fuel mixture. 1/2 turn is a large adjustment step in most cases.



This view depicts rear end of the injection pump with the pneumatic governor housing, altitude compensator, and oil filter removed. Access -looks- easy but with everything in place, it's cramped quarters. But for a clear view of the smoke setscrew, this picture serves that purpose pretty well.

IF you have the typical PH8A tall filter installed, access to the lock nut requires removal of the oil filter. I use a slightly shorter oil filter (Purolator 14670 or NAPA Gold 1068) which allows me to fit a deep 14mm socket on the lock nut with ease.

The altitude compensator tip must be backed away sufficient to prevent contact with the fuel lever linkage. If the altitude compensator tip is resting firmly on fuel lever linkage, then you will not be able to further -richen- the fuel lever position using the smoke setscrew. See the Altitude Compensator thread.

Last edited by philip 15 years ago, edited 1 time in total.
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"
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