Just wanted to find out what you guys were running as far as tuning on your MC2100 carbs (on the 258)? I can't get this one right. I have my needles at 3 turns out. Is there anything else I can do. It runs fine at cruising speed/off idle, but does not idle and will die on you when you stop. I put this on there to stop all that non-sense!! The last one I did worked perfect.

We just installed a Reman one from Tomco via Napa Auto Parts. It was done on a complete overhaul along with the Nutter by pass and appropriate timing changes on an 88 YJ 258/BA10/231/4.56's 32" tires. It had a bit of a rough idle but more troublesome was a dead spot upon accelleration @ approx 1800 RPM. We removed the carb and dissassembled for inspection assuming some crap from the fuel system got in or something was wrong with the new carb. We were greeted with two different size jets/nozzles and a bent power valve fresh off a reman. With those items replaced, carb tuning redone and retiming it is now the snappiest 258 with a carb we have worked on.
Long story short, check for uneven fuel delivery due to poor or improper parts in the carb. HTH


BTW, have you checked for vacuum leaks?

Those carbs don’t seem to be real picky about where you have the needles set. I think that there is probably something else wrong. I think I set mine at 2.5 turns when I rebuilt it and have never touched the needles again.

Well I rebuilt the carb and I have built them before. I am pretty sure I have all the vacuum issues dealt with, but will double check. In my previous experience with the carbs tuning is not even an issue so this one stumps me.