Engine Specifications

The engines used in the 1941 Buicks were introduced in the 1930s: the larger 320 cubic inch unit having been introduced in 1936 and the 248 cubic inch engine in 1937. Both were in-line eight cylinder designs with Buick's traditional overhead valve arrangement. The smaller engine, used in the Special (40) and Super (50) series, made 115 horsepower with a single carburetor, and 125 with dual carburetion (standard on Super). The larger engine generated 165 horsepower with the standard dual carburetors. This was the most horsepower of any American car that year, and was used in the Century (60), Roadmaster(70) and Limited (90) series.

	Special (Series 40)	Super (Series 50)	Century (Series 60)	Roadmaster (Series 70)	Limited (Series 90)
DIMENSIONS
Type	OHV in-line eight cylinder	OHV in-line eight cylinder	OHV in-line eight cylinder	OHV in-line eight cylinder	OHV in-line eight cylinder
Bore	3-3/32"	3-3/32"	3-7/16"	3-7/16"	3-7/16"
Stroke	4-1/8"	4-1/8"	4-5/16"	4-5/16"	4-5/16"
Displacement	248 CID	248 CID	320.2 CID	320.2 CID	320.2 CID
Compression Ratio	6.5:1 7.0 to 1 (with dual carbs)	7.0 to 1 (dual carbs standard)	7.0 to 1 (dual carbs standard)	7.0 to 1 (dual carbs standard)	7.0 to 1 (dual carbs standard)
Induction	1x2 bbl Stromberg or Carter carburetor (dual carburetors optional)	2x2 bbl Stromberg or Carter carburetors	2x2 bbl Stromberg or Carter carburetors	2x2 bbl Stromberg or Carter carburetors	2x2 bbl Stromberg or Carter carburetors
Horsepower	115 @ 3500 RPM 125 @ 3800 RPM (with dual carbs)	125 @ 3800 RPM	165 @ 3800 RPM	165 @ 3800 RPM	165 @ 3800 RPM
Torque	210 @ 2000 RPM 215 @ 2000 RPM (with dual carbs)	215 @ 2000 RPM	278 @ 2200 RPM	278 @ 2200 RPM	278 @ 2200 RPM
Firing Order	1-6-2-5-8-3-7-4	1-6-2-5-8-3-7-4	1-6-2-5-8-3-7-4	1-6-2-5-8-3-7-4	1-6-2-5-8-3-7-4
Engine Weight	721.5 lbs.	721.5 lbs.	862.3 lbs.	862.3 lbs.	862.3 lbs.
Main Bearings	5	5	5	5	5
Intake Valve Size	1-17/32"	1-17/32"	1-25/32"	1-25/32"	1-23/32"
Exhaust Valve Size	1-11/32"	1-11/32"	1-7/16"	1-7/16"	1-7/16"
Valve Lift (intake)	.348"	.348"	.347"	.347"	.347"
Valve Lift (exhaust)	.348"	.348"	.342"	.342"	.342"
Intake Duration	13° BTDC/68° ATDC	13° BTDC/68° ATDC	14° BTDC/71° ATDC	14° BTDC/71° ATDC	14° BTDC/71° ATDC
Exhaust Duration	55° BTDC/22° ATDC	55° BTDC/22° ATDC	56° BTDC/25° ATDC	56° BTDC/25° ATDC	56° BTDC/25° ATDC
Valve Lash (hot)	.015"	.015"	.015"	.015"	.015"
Distributor Point Opening	.015"	.015"	.015"	.015"	.015"
Dwell	31°	31°	31°	31°	31°
Spark Plug Gap	.025" to .030"	.025" to .030"	.025" to .030"	.025" to .030"	.025" to .030"
Spark Plug Type	AC type 104 10mm	AC type 104 10mm	AC type 104 10mm	AC type 104 10mm	AC type 104 10mm

DRIVELINE
1st Gear	2.67:1	2.67:1	2.39:1	2.39:1	2.39:1
2nd Gear	1.66:1	1.66:1	1.53:1	1.53:1	1.53:1
3rd Gear	1:1	1:1	1:1	1:1	1:1
Reverse	3.02:1	3.02:1	2.53:1	2.53:1	2.53:1

Rear Axle Ratio (std./opt.)	4.4:1 / 3.9:1	4.1:1 / 3.9:1	3.9:1 / 3.6:1	3.9:1 / 3.6:1	4.2:1

RECOMMENDED FLUIDS
Engine Oil	SAE 20W	SAE 20W	SAE 20W	SAE 20W	SAE 20W
Transmission Oil	SAE 90	SAE 90	SAE 90	SAE 90	SAE 90
Differential Oil	SAE 90	SAE 90	SAE 90	SAE 90	SAE 90

CAPACITIES
Oil Capacity (quarts)	6 (refill) 8 (dry)	6 (refill) 8 (dry)	8 (refill) 10 (dry)	8 (refill) 10 (dry)	8 (refill) 10 (dry)
Fuel Capacity	18 gallons	18 gallons	18 gallons	18 gallons	21 gallons
Cooling System Capacity	14-1/4 quarts w/ heater 13 quarts w/o heater	14-1/4 quarts w/ heater 13 quarts w/o heater	18 quarts w/ heater 16-3/4 quarts w/o heater	18 quarts w/ heater 16-3/4 quarts w/o heater	18 quarts (heater standard)
Transmission Capacity	1-3/4 pints	1-3/4 pints	2-1/2 pints	2-1/2 pints	2-1/2 pints
Rear Axle Capacity	3 pints	3 pints	3 pints	3 pints	4 pints
Steering Gear Capacity	15 oz.	15 oz.	18 oz.	18 oz.	18 oz.

TORQUE SPECS.
Head Torque	65-70 lb.-ft.	65-70 lb.-ft.	65-70 lb.-ft.	65-70 lb.-ft.	65-70 lb.-ft.
Main Torque	115-120 lb-ft.	115-120 lb-ft.	115-120 lb-ft.	115-120 lb-ft.	115-120 lb-ft.
Rod Torque	45-50 lb.-ft.	45-50 lb.-ft.	60-65 lb.-ft.	60-65 lb.-ft.	60-65 lb.-ft.
Flywheel Torque	40 lb.-ft	40 lb.-ft	55 lb.-ft	55 lb.-ft	55 lb.-ft