How to straighten a carb needle the easy way

Place to put all stickies after a month.

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Location: Hood River, OR

How to straighten a carb needle the easy way

Post by exit64 »

So this morning I decided to fix my rear carb that has a sticky piston. No problem right? I undo the dome and am going to check the needle on the bottom of the piston and make sure it is straight. As I pull off the dome the suction from my properly filled dash pot pulls the piston out of the carb body and then promptly lets go. Well I know for sure now that the needle definatly has a bend in it. Crap, will this comedy of errors never end? Time to show this needle who's boss. First I removed the needle from the piston. I used a wood vice with a soft piece of pine between the jaws to grab the needle while I GENTLY turned the piston while pulling. Comes out like a loose tooth. I then put the needle on the flatest surface I have in my shop, my table saw, and roll it to see how bad the bend is. OK so it bowed in the middle by about 2mm. Not the end of the world. I take a piece of maple that is perfectly flat and use this to roll the needle back and forth over the saw table until the bend is gone. I used the edge of the table and let the shoulder part of the needle hang over so as not to give that part a taper. The brass is very soft. Now for the cool part. I want the needle to not only be straight but also have no wobble in it . To check this I chuck it up in the drill press and spin it by hand. Mine had about a 3mm wobble in it. That's not good. Now turn on the drill press at the lowest speed and while the needle is turning take the afore mentioned piece of maple and press on the lower end of the needle and flex it to the side about 1/16-1/8th of an inch and then release pressure. The needle should be perfectly straight while spinning if you did it right. If not pressure it again until the desired results are obtained. Don't forget to wear safety glasses any time you use power tools.
This car is making me remember all sorts of shop trick that I thought I had forgotten :shock: Hope this saves someone some time and money at some point. Oh, and the carb works smoother than it ever did. Mission accomplished.
1967.5 SPL 311-14542 Pieces-parts
1969 SRL 311-09979
1966 411 Blackbird....Stay tuned.
1971 B110 757213 About to unleash 69 HP @6000 RPM
A carburetor man in a fuel injection world.
"Ripping the Bring* and sanding it round"

Post by katman »

Great idea, will try putting carb needles in my drill press to see if they're straight. Just so happens I was working on my carbs today. Although I managed to break the head off one of the brass screws holding the throttle plate. Sigh...