Triumph Repair: Stromberbg carb on 1974 Spitfire, allen screw, set screw

Question
I find myself having to add oil about every week or two to my dashpot on my carberator. My friends who have British  cars say they add oil maybe once a year. Where is my oil going? Is there a bad seal or something?

Answer
Hi Jim,
If your Stromberg has the adjustable needle there is an "O" ring on the adjusting screw. It is held in by a speed nut type ring. To get it out and replace the "O" ring you need to note the position of the needle by counting the number of rotations (clockwise)of the adjusting screw (3mm Allen) down in the tube. Then take a tube drift (I use a short piece of brake line) and drive the jet assembly out the top of the tube) (note that a set screw is in the side of the piston at the bottom which acts as a guide to keep the jet assembly from rotating when adjusting the needle, this does not normally need to be removed but in some cases I found it necessary)

Catch the speed nut ring as it comes out of the top and then the whole jet needle assembly will come out and you can see the "O" ring on the adjusting screw. If you can't find a new "O" ring at any of the British car parts suppliers you can match one up at most bearing companies. When you replace the unit the adjusting screw will be locked down (clockwise) so after you get it seated with the set screw in it's grove, you will need to reset the 3mm Allen screw to the exact number of turns out that it took to screw all the way in to get you original mixture adjustment.

Also, the oil level will not stay "full" so the way to gauge if it needs oil is to unscrew the top cap and lift the pin up and push it down and if you feel hydraulic resistance there is enough in it. I found that an average time needing oil is about every three or four months on both Strombergs and SUs

Howard