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Torques for standard metric and imperial bolts


All manufacturers use standard bolt torques for general specifications, and list exceptions to them for bolts requiring special attention or torques, e.g. cylinder head bolts and main bearing cap bolts.


More about standard bolt torques

Diesel engine manuals and specifications

at Barrington Diesel Club


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Your Detroit Diesel Specs

Basic specs are open to everyone and include images, displacement, dimensions and weight, essential bolt tightening torques, the characteristics of the engine like its power and torque.
Essential bolt tightening torques are the main bearing cap bolt torque, the connecting rod cap bolt torque and the cylinder head bolt torques.


Some Popular Engine Specs


Standard Bolt torques for imperial and for metric bolts

Standard Torques for Imperial Bolts

Barrington Diesel Club - Logo Imperial High Tensile Bolts - Table of Standard Torques
Image Grade 5 Imperial bolts IMPERIAL Grade 5 bolts, allow a torque variance of ± 5% either way      . image g8 bolt head IMPERIAL Grade 8 bolts, allow a torque variance of ± 5% either way     
Bolt size Thread lb.ft Nm . Bolt size Thread lb.ft Nm
1/4 inch NC 6 8 . 1/4 inch NC 8 11
1/4 inch NF 7 10 . 1/4 inch NF 11 13
5/16 inch NC 12 16 . 5/16 inch NC 16 21
5/16 inch NF 13 17 . 5/16 inch NF 17 24
3/8 inch NC 25 32 . 3/8 inch NC 33 44
3/8 inch NF 28 37 . 3/8 inch NF 37 50
7/16 inch NC 37 48 . 7/16 inch NC 48 65
7/16 inch NF 45 60 . 7/16 inch NF 59 80
1/2 inch NC 54 71 . 1/2 inch NC 73 100
1/2 inch NF 65 90 . 1/2 inch NF 88 120
9/16 inch NC 70 95 . 9/16 inch NC 95 130
9/16 inch NF 85 115 . 9/16 inch NF 112 152
5/8 inch NC 108 145 . 5/8 inch NC 142 193
5/8 inch NF 130 175 . 5/8 inch NF 173 235
3/4 inch NC 185 250 . 3/4 inch NC 245 332
3/4 inch NF 220 300 . 3/4 inch NF 295 400
7/8 inch NC 310 422 . 7/8 inch NC 415 563
7/8 inch NF 360 490 . 7/8 inch NF 480 650
1 inch NC 440 595 . 1 inch NC 585 795
1 inch NF 518 700 . 1 inch NF 690 930
Bolt size Thread lb.ft Nm . Bolt size Thread lb.ft Nm
Image Grade 5 Imperial bolts IMPERIAL Grade 5 bolts, allow a torque variance of ± 5% either way . Image Grade 8 Imperial bolts IMPERIAL Grade 8 bolts, allow a torque variance of ± 5% either way

Standard Torques for Metric Bolts


Barrington Diesel Club - Logo Metric Bolts - Table of Standard Torques (± 5% Nm)
Grade  8.8 10.9 12.9 . Grade  8.8 10.9 12.9
Diameter  Dry Threads - torque  . Diameter  Oiled Threads - torque 
M5 6 9 10 . M5 4.5 6.5 7.5
M6 10 15 18 . M6 7.5 11 13
M8 25 35 45 . M8 18 25 30
M10 50 75 85 . M10 35 55 65
M12 85 130 150 . M12 65 95 110
M14 140 205 240 . M14 100 150 175
M16 215 315 370 . M16 160 235 275
M20 435 620 725 . M20 320 455 535
M24 750 1070 1255 . M24 555 790 925
Diameter  Dry Threads - torque  . Diameter  Oiled Threads - torque 



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