230SL FIP Idle Mixture Knob Advice

[captainslow]

So, I was seeking to cure a super rich running idle. My first clue I might need to play with the mixture knob was that there was no knob… apparently there is supposed to be a knob and a captured spring living down on the injection pump! Someone at some point in time sheared my knob off and didn’t bother to fix it. When I went to try and spin the shaft of the knob by hand it wouldn’t turn. A mini vicegrip later I was able to start moving it CCW to lean everything out. It has a pretty nice idle mixture right now BUT now I can’t disengage the shaft from the adjustment on the end of the FIP. I’m assuming it got caught when I was messing with it because it didn’t have a spring to pop it back out, and unscrewed the idle mixture to a point where the screw now sits too proud to disengage. Does this sound reasonable? How hard is it to get the big nut off; is it super tight?

The idle fuel mixture seems great when applying the split linkage test. If it’s backed out too far now I assume this probably means it’s a bad CSV? It gets fairly decent mileage as far as I can tell on the freeway so I hadn’t expected it to be a leaky a CSV. It just seemed to have a rich idle!

[wwheeler]

Not sure I have ever heard of a missing idle mixture knob. The first order of business for me would be to remove the large nut (buy a socket or wrench) and replace the idle mixture knob. Then you need to assess if there is any damage to the part that the idle screw engages. Get that fixed and go from there.

[DaveB]

I have a parts 250 pump that likely has the correct knob - can send for postage cost, let me know if you need it.
By the way did/will you put your 5-speed transmission in the car?

[captainslow]

Thanks guys, I agree that’s definitely the best course of action. Any idea what size socket is required? I can throw a caliper on it but if anyone has it handy I can just order the socket from my PJs!

Dave I will definitely take you up on that. Logically it follows I’ll need the entire end nut because the wheel/spring is either likely swaged or welded together as an assembly. Is that okay? I’ll happily pay you for the convienece of not having to search eBay, not just for shipping. I’ll get the nut off and see if there are any other damaged bits you might be able to supply if you are willing to part with them.  Also I think you have me confused with someone else. I wish I had a 5 speed to drop in! The only kustom with a k thing I’ve done so far was install a clutch fan on a 230 which turned out to not be trivial.

[DaveB]

No problem, have a look and let me know what you need. I think the back plate on this pump is complete but I’m away from home so haven’t checked.
And yes, must have been a mistaken identity.