Johnson Service Bulletin SB-982 - Orifice Plug (High Speed Jet) Chart

Issued October 10, 1963, this factory chart identifies current and discontinued carburetor high-speed jet orifice plugs by part number, thread type, engine application and year. The two original factory pages are reproduced below with searchable, linkable table entries.

Johnson Motors Service Bulletin header

October 10, 1963

SUBJECT: ORIFICE PLUG (HIGH SPEED JET) CHART.

All current as well as non current carburetor orifice plugs are listed here along with their identifying characteristics. The illustrations show two different thread types that are used.

Factory diagrams comparing full-thread and half-thread high speed jet orifice plugs
ORIFICE PART
NUMBER		IDENTIFICATIONMODEL USAGEH.P.YEAR
309345Stamped #30
Full thread		JW-18R31963
310758Stamped #28
Full thread		JW & JH-19A31964
309389Stamped #40
Full thread		CD-21A5½1964
309681Stamped #48
Full thread		MQ-10S9½1964
309415Stamped #64
Full thread		FD-18E181964
307781One groove on
long end - one
groove on short
end.
Short thread		RD-23401961
307065Plain
Short thread		V4S-10
V4S-11		50
50		1958
1959
307532One groove on
long end.
Short thread		V4S-12751960
Page 2
SB-# 982
ORIFICE PART
NUMBER		IDENTIFICATIONMODEL USAGEH.P.YEAR
554049Two grooves on
long end.
Short thread		VX-10S601964
309517Stamped #72
Full thread		V4A-13
V4A-14
V4A-15
V4A-16		75
75
75
75		1961
1962
1963
1964
307813One groove on
slotted end.

Short thread		V4S-13
V4S-14
V4S-15
V4S-16

RD-RK-24		75
75
75
75

40		1961
1962
1963
1964

1962
309935Stamped #68
Full thread		RD-RK-25-26

V4M-10		40

90		1963-64

1964

The following orifice plugs are used in accessory adjustable high speed jet kits. Note that here, the part number of the accessory kit in which the respective orifice plug is used has also been given.

ORIFICE PART
NUMBER		IDENTIFICATIONMODEL USAGEH.P.ACCESSORY
KIT NO.		YEAR
310575Stamped A34
Full thread		For JW-18
For JW-JH-19A		3
3		379627
379627		1963
1964
309790Stamped A74
Full thread		For RD-23
For RD-RK-24
For RD-RK-25
For RD-RK-26

For V4S-V4A-13
For V4S-V4A-14
For V4S-V4A-15
For V4S-V4A-16		40
40
40
40

75
75
75
75		379188
379188
379188
379188

379189
379189
379189
379189		1961
1962
1963
1964

1961
1962
1963
1964

Sincerely,

JOHNSON MOTORS

Robert Compton
Administrative Assistant

RC:eb

NOTE: Post on all indexes.

Parts reference

Each orifice plug has a direct anchor for future cross-references. For example, part 309517 and part 309790. Thread types and factory application details are preserved in the tables above.