First post here, and I’ve jumped in with grease up to the elbows…

• Car: ‘82 Australian delivery 280SE (W126), SLS, AIR pump (disabled) and EGR. Close to 300K (~180K miles). Later 15” wheels but otherwise as when sold.
  
• Summary: Sorting the worst parts for a friend who bought in with eyes shut, looking for help with items that either received “expert attention” or have been badly neglected.
  
• Immediate Problem: Throttle plate (butterfly) found misadjusted.

Note: I have not touched the mixture screw, I promise!

Chasing a number of poor performance issues, identified a sticky throttle. After dismantling, cleaning, re-greasing every point in the linkage from the pedal base to the butterfly, I removed the injection unit as a a whole to clean and inspect the throttle plate.

The plate was shutting so hard on its spring, it was starting to chafe a groove into the throttle bore. The stop locknut was loose and stop setscrew about 30 thou clear of the lever! Also, the vacuum line from vapour canister to throttle was open where it’s rubber end-piece was 70% torn apart. This detail might go towards explaining some of the issues.

I removed the throttle body, gave it a light clean and checked all vacuum passages were fully clear. Refitted the TPS by carefully aligning the witness marks its large flatwasher had made, applied a super-light film of Permatex No.3 to the gasket and bolted it back down. Throttle stop is currently set close as possible without binding - kerosene would drain slowly through but it’s near enough airtight to a running motor.

Is this set right? I have literally spent hours over several days, trawling the internet for throttle stop specs. One forum for another marque mentioned a notional gap of 15 thou (at widest point) from throttle plate to bore.

My confusion is made worse by not knowing the idle air valve’s direction of airflow - whether it goes into the injector assembly’s chamber or starts from there.

Advice on both the stop setting and idle airflow direction would be really appreciated, and I thank anyone who offers advice.

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