MTFCA Forum

How do you tighten a late carb needle? The carb is a sway back NH. The car is a '14 with the large brass disk on the other end which adjusts itself as I drive and not always the way I feel it ought to be adjusted. Lately I have been using a block of packing foam to hold it in place.

The '23 also with a swayback NH has a top nut that has grooves so it will tighten the needle as the nut is tightened into the casting. This nut has no grooves and does not tighten the needle no matter how hard it gets tightened.

Paul

You press the arms in a little to add drag to the needle.

The arms press on the nut and not the needle unless I'm missing something. How would that keep the needle from migrating to a new position?

I know its gotta be simple but I still don't get it.

Paul

Trust him it works.

The pressure from the arms creates the friction so the needle wont turn on its own.

The arms are part of the cross piece attached to the top of the needle. They are a unit. So just wind the needle out and pinch the sides in a bit. Job done.

Allan from down under.

If you can get the needle adjusted to the point where the engine runs smoothest when it is warmed up, but the needle moves as you drive along and gets out of adjustment, the arms needed to be tightened as Allan says. Then adjust to run smooth and it should stay in adjustment until you turn the nob.
Norm

As posted by others, crimp the fingers over the cylinder of the lock nut to tighten drag of the spray needle. Easiest done by removing the needle, crimp some, re-fit needle , remove again and test and crimp to get the right tension.

I just today ran into a similar problem today with the late model NH repro adjusting needle - near 3/16" shorter than original and bottomed out on the adjusting nut to prevent the needle from seating to make a proper mixture adjustment. A couple minutes in the lathe to shorten the nut shoulder made for more adjustment.

I have the same problem on occasion. I have a 1-piece valve cover and oil mist from the throttle rod hole lubricates the fingers on the needle. Cleaning it is part of my normal routine.

Thanks everyone, once I took a second look I could see what was happening and understand what needed to be done. No amount of clamping with the biggest channel locks I have would compress it enough to make any difference so the next step will be to remove the assembly and use the big vice. If that doesn't do it . . .

Paul

Paul, once you remove the needle from the brass nut, the fingers are easily bent to tighten their grip. Using channel locks with the fingers around the brass nut will do no good, but you already know that.

Mark, thanks for the clarification. I knew I had no luck adjusting the tension but its good to know that just removing it will make the difference. I would like to retire the block of black foam under the dashboard knob.

Paul