GMC gasoline V8 60° 637 CID (10.4 L) 637 engine DIY maintenance and service manual

General Information

GMC gasoline V8 60° 637 CID (10.4 L) 637 is an 637 in³ (10.44 L) internal combustion reciprocating V8 engine. It has bore/stroke ratio of 5.125 in × 3.86 in (13.018 cm × 9.8 cm), and uses 7.5:1 compression. This engine was rated 250 hp (186.42 kW) at 2800 rpm. It was used in Chevrolet and GMC cars.

Engine Performance Rating

SAE J1349 (SAE Net)

GMC gasoline V8 60° 637 CID (10.4 L) 637 engine performance rating according to SAE J1349 (SAE Net) standard.
Parameter	Output
Power Rating	250 hp (186.42 kW) at 2800 RPM

Specifications

General

GMC gasoline V8 60° 637 CID (10.4 L) 637 engine general specifications.
Parameter	Value
Type	Internal Combustion Reciprocating
Fuel Type	Gasoline
Cylinder Configuration	V8
Engine Displacement	10.44 L637 in³637 in³
Bore	13.018 cm5.125 in5.125 in
Stroke	9.8 cm3.86 in3.86 in
Compression Ratio	7.5:1
Firing Order	1-8-4-3-6-5-7-2
Curb Idle Speed	400-425 RPMs

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Compression

GMC gasoline V8 60° 637 CID (10.4 L) 637 engine compression.
Parameter	Value
Compression (standart)	8.51 atm.125 Psi125 Psi

Spark Plugs and Wires

GMC gasoline V8 60° 637 CID (10.4 L) 637 spark plugs and wires specifications.
Parameter	Value
Spark Plugs	AC Delco C42N
Spark Plug Gap	889 μm0.035 in0.035 in

Engine head and valvetrain

GMC gasoline V8 60° 637 CID (10.4 L) 637 engine head and valvetrain specifications.
Parameter	Value
Valvetrain Type	OHV
Valves per Cylinder	2

Air Intake

GMC gasoline V8 60° 637 CID (10.4 L) 637 air intake specifications.
Parameter	Value
Air Intake Method	Naturally Aspirated

Fuel Injection

GMC gasoline V8 60° 637 CID (10.4 L) 637 fuel injection specifications.
Parameter	Value
Injection Type	Carburetor

Valve Timings

GMC gasoline V8 60° 637 CID (10.4 L) 637 valve timings.
Parameter	Value
Intake Opens	27° B.T.D.C.
Intake Closes	61° A.B.D.C.
Intake Duration	268°
Exhaust Opens	82° B.B.D.C.
Exhaust Closes	36° A.T.D.C.
Exhaust Duration	298°
Valves Overlap	206°
Ignition Timing	10° B.T.C.

GMC gasoline V8 60° 637 CID (10.4 L) 637 valve timing diagram.

Engine Specifications

Condition	Value

expand_moreSpark plugs


Tightening torque	31.18–36.61 N⋅m23–27 lbf⋅ft23–27 lbf⋅ft

expand_moreIgnition distributor


Dwell angle	29–31

expand_morePoint opening


New	482.6 μm0.019 in0.019 in
Used	406.4 μm0.016 in0.016 in


Contact lever spring tension	538.64–652.04 g19–23 oz19–23 oz