RCB 9C-327

Rochester Carburetors 1958 CHEVROLET

TRIPLE TWO BARREL CARBURETOR INSTALLATION ADJUSTMENTS AND SPECIFICATIONS

BULLETIN 9C-327

PAGE 5 OF 5 DATE: 1/15/58

For basic operation and description of systems, refer to Bulletin 9 D-10-57A.

QUICK REFERENCE SPECIFICATIONS


		FRONT	CENTER	CENTER	REAR	TUNE-UP
CARBURETOR No.		7011951	7012503 Syn.	7011952 A.T	7011953
		7012851			7012853
		7012851			7012853
SMALL VENTURI		1/8"	1/8"	1/8"	1/8"
LARGE VENTURI		1-1/4"	1-3/16"	1-3/16"	1-1/4"
MAIN METERING JETS		.063	.061	.059	.055	Spark Plug Gap—.035"
IDLE NEEDLE HOLES		—	.046	.040	—	Spark Plug Gap—.035"
SEC.	LOWER	—	.033	.028	—	Breaker Point Gap—.016"
DISCHARGE	MIDDLE	—	.029	.029	—	Cam Dwell—28°-32°
HOLES	UPPER	—	.035	.032	—	Ignition Timing 4° BTDC Idling R.P.M.—A.T. 425 Dr.
SPARK DRILLINGS		—	[2] .040	(2) .040	—
PUMP JETS		.030	.026	.026	.030
POWER RESTRICTIONS		—	.048'	.051	—	Syn. 475 Neut.
CHOKE	CHANNEL	—	.089	.089	—
RESTRICTIONS	BY-PASS	—	.040	.040	—
IDLE TUBE RESTRICTION		—	.029	.031	—
ADJUSTMENTS		DIMENSION	DIMENSION	DIMENSION	DIMENSION	GAUGE No.
FLOAT LEVEL		1-5/16"	1-1/4"	1-1/4"	1-5/16"	Center Carburetor BT-129 Front & Rear Carburetor BT-136
FLOAT DROP		1-29/32"	1-29/32"	1-29/32"	1 -29/32"	BT-129 or Scale
PUMP ROD		15/16"	15/16"	15/16"	15/16"	BT-136
VACUUM SWITCH		—	(.031) 1/32"	(.031)1/32"	—	Feeler Gouge or Scale
AUTOMATIC CHOKE			INDEX	INDEX
CHOKE ROD		—	.089	.089	—	BT-108
UNLOADER		—	.360	.360		BT-108
CHOKE LOCKOUT		.030		—	—	Feeler Gauge
CHOKE CONTOUR		.015	—	—	—	Feeler Gauge

CARBURETOR TOOLS AND GAUGES AS LISTED ARE AVAILABLE THROUGH UMS DISTRIBUTORS

Rochester Carburetor

A GENERAL MOTORS PRODUCT — A UNITED MOTORS LINE

CO, WD, 131, 149, 9X, 9FR, 9FD

FORM NO. 1255 I.P.5.

PRINTED IN U.S.A.