Author Topic: Needles for needle valves in carburettors.  (Read 346 times)

Offline Trevorc

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Needles for needle valves in carburettors.
« on: February 01, 2021, 07:46:20 PM »
Hello
Does anybody have advice on type and source of suitable needles for use in needle valves on carb.
My current project, an Anzani Y , specifies a 1/16 inch hole in jet and a 1/32 inch diameter tapered needle.
Have used small diameter sewing needle BUT these have a curved point not a nice uniform taper as the drawings suggest. Using sewing needle means that the control of fuel flow is either “ all or nothing” there is not incremental increase in flow are at exit from jet.
Have others encountered similar problems? What was solution?
Thanks in advance for any help.
Trevorc

Offline cnr6400

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Re: Needles for needle valves in carburettors.
« Reply #1 on: February 01, 2021, 08:34:25 PM »
I've made a number of successful carb needles by placing the drill rod or music wire needle in the lathe chuck, The Dremel tool with an alum oxide wheel is placed in a holder on the toolpost, and the compound rest of the lathe set to the needed taper angle. My lathe is an old worn out 9" South Bend. I use the compound rest's leadscrew to move the grinding wheel across the needle end (using very fine feeds) until the needle is finished to a fine point and nice smooth finish. Very slow to do, and limited to about 1.5" of taper, but gives a good result. The lathe ways are covered with a cloth during these ops to keep the grinding dust out.

Offline Brian Rupnow

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Re: Needles for needle valves in carburettors.
« Reply #2 on: February 01, 2021, 09:05:33 PM »
I use sewing needles. You can buy a pack of various sizes from any fabric shop. I never had luck trying to make my own needle.---Brian

Offline Ramon

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Re: Needles for needle valves in carburettors.
« Reply #3 on: February 01, 2021, 10:52:38 PM »
Hi Trevor, I've described the method I use a few times on here - such as https://www.modelenginemaker.com/index.php/topic,1334.120.html - scroll to post #125

I've made quite a few needles in this manner all of which have worked well with the basic needle valve assembly used in IC diesel engines. Simple to do and effective.

Might be worth a look ?

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline nj111

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Re: Needles for needle valves in carburettors.
« Reply #4 on: February 02, 2021, 09:56:54 AM »
Interesting link, thank you Ramon
Nick