Carburetor needle valve adjustment limiter cap and method of use

For a carburetor having a valve for adjusting fuel flow by rotating a shank of the valve projecting from the carburetor, an adjustment limiting apparatus comprising a body having a passage therein constructed and arranged to telescopically received over an end of the shank, a recess on one of the shank and in said passage of said body, a projection on the other of said shank and in said passage of said body, at least one of said recess and said projection being substantially circumferentially continuous, said recess and projection being constructed and arranged so that when said body is telescoped over the shank in a first position, said projection is received in said recess so that the shank can be rotated relative to said body and said body is retained on the shank, a head on the shank, an engagement portion in the passage of said body which engages with said head when said body is received on the shank in a second position axially spaced from said first position to couple said body to the shank for rotation only in unison therewith, an arm fixed to said body and projecting generally radially thereof and constructed and arranged to limit the extent of rotation of the shank to less than one complete revolution at least when said body is in said second position by engagement of said arm with at least one stop carried by the carburetor and projecting into the arcuate path of rotary movement of said arm, orienting means operably associated with said body and constructed and arranged to angularly orient said arm of said cap relative to the shank of the valve and the one stop operably associated with said arm when the cap is in said first position on the shank and while the cap is being moved from the first position to the second position on the shank to couple the shank with the body of the cap, whereby when said body is telescoped over the shank and in said first position, the shank can rotate relative to the body while retained thereon and when in said second position the shank and said body can be rotated only in unison and said arm is engagable with at least one stop to limit the rotation of the shank and said body to less than one complete revolution to thereby limit adjustment of the valve.

A method of adjusting the fuel flow of a carburetor and limiting further adjustment thereof comprising:

• (a) providing a carburetor having at least one valve for adjusting fuel flow by rotating a shank of the valve projecting from the carburetor,
• (b) placing the carburetor in a test stand and rotating the shank to adjust fuel flow to a desired predetermined value,
• (c) providing a limiter cap having a body with a passage therein constructed and arranged to be telescopically received over an end of the shank, the body having retainer means in the passage constructed and arranged to retain the body in a first position on the shank with the body being freely rotatable relative to the shank, engagement means in the passage and constructed and arranged to engage with the shank when the body is telescoped over the shank and in a second position axially spaced from the first position to couple the shank with the body so that the shank and body can rotate only in unison when the body is in the second position, an arm fixed to the body and projecting generally radially therefrom and constructed and arranged to limit the extent of rotation of the shank to less than one revolution when the body is telescoped over the shank and in the second position by engagement of the arm with at least one stop carried by the carburetor, and orienting means operably associated with said body and constructed and arranged to angularly orient said arm of said cap relative to the shank of the valve and the one stop operably associated with said arm when the cap is in said first position on the shank and while the cap is being moved from the first position to the second position on the shank to couple the shank with the body of the cap,
• (d) positioning the cap on the shank with the body telescoped over the shank and in the first position thereof on the shank,
• (e) mounting the carburetor on an engine with which it will be utilized,
• (f) thereafter while operating the engine making any further needed adjustment of the valve by rotating the shank to fine tune fuel flow to optimize predetermined operating parameters of the engine,
• (g) utilizing the orienting means to angularly orient the cap while in the first position on the shank in a predetermined position relative to the fine tuned fuel flow position of the shank resulting from step (e), and
• (h) after step (g) moving the body to the second position on the shank to thereby limit the extent of any subsequent adjustment of the valve by the arm of the cap bearing on at least one stop carried by the carburetor and disposed in the arcuate path of movement of the arm at least while the cap is in the second position on the shank.