Mechanical Gas Fuel System G5.9, G8.3, G855 – Master Repair Manual 018-009   Capscrew Markings and Torque Values

General Information

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 CAUTION 

When replacing capscrews, always use a capscrew of the same measurement and strength as the capscrew being replaced. Using the wrong capscrews can result in engine damage.

Metric capscrews and nuts are identified by the grade number stamped on the head of the capscrew or on the surface of the nuts. U.S. Customary capscrews are identified by radial lines stamped on the head of the capscrew.

The following examples indicate how capscrews are identified:

SMALL | MEDIUM | LARGE

  • Always use the torque values listed in the following tables when specific torque values are not available.
  • Do not use the torque values in place of those specified in other sections of this manual.
  • The torque values in the table are based on the use of lubricated threads.
  • When the ft-lb value is less than 10, convert the ft-lb value to in-lb to obtain a better torque with an in-lb torque wrench. Example: 6 ft-lb equals 72 in-lb.

SMALL | MEDIUM | LARGE

  • Always use the torque values listed in the following tables when specific torque values are not available.
  • Do not use the torque values in place of those specified in other sections of this manual.
  • The torque values in the table are based on the use of lubricated threads.
  • When the ft-lb value is less than 10, convert the ft-lb value to in-lb to obtain a better torque with an in-lb torque wrench. Example: 6 ft-lb equals 72 in-lb.

Capscrew Markings and Torque Values – Metric

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SMALL | MEDIUM | LARGE

Body Size
Torque
Torque
Torque
Diameter
Cast Iron
Aluminium
Cast Iron
Aluminium
Cast Iron
Aluminium
mm
N•m
ft-lb
N•m
ft-lb
N•m
ft-lb
N•m
ft-lb
N•m
ft-lb
N•m
ft-lb
 6
  9
  5
  7
  4
 13
 10
  7
  4
 14
  9
  7
  4
 7
 14
  9
 11
  7
 18
 14
 11
  7
 23
 18
 11
  7
 8
 23
 17
 18
 14
 33
 25
 18
 14
 40
 29
 18
 14
10
 45
 33
 30
 25
 65
 50
 30
 25
 70
 50
 30
 25
12
 80
 60
 55
 40
115
 85
 55
 40
125
 95
 55
 40
14
125
 90
 90
 65
180
133
 90
 65
195
145
 90
 65
16
195
140
140
100
280
200
140
100
290
210
140
100
18
280
200
180
135
390
285
180
135
400
290
180
135
20
400
290
 —
 —
550
400
 —
 —
 —
 —
 —
 —

Capscrew Markings and Torque Values – U.S. Customary

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SMALL | MEDIUM | LARGE

Capscrew Body Size
Cast Iron
Aluminium
Cast Iron
Aluminium
 
N•m
ft-lb
N•m
ft-lb
N•m
ft-lb
N•m
ft-lb
 1/4 – 20
9
7
8
6
15
11
8
6
 1/4 – 28
12
  9
  9
  7
 18
 13
  9
  7
5/16 – 18
20
 15
 16
 12
 30
 22
 16
 12
5/16 – 24
23
 17
 19
 14
 33
 24
 19
 14
 3/8 – 16
40
 30
 25
 20
 55
 40
 25
 20
 3/8 – 24
40
 30
 35
 25
 60
 45
 35
 25
7/16 – 14
 60
 45
 45
 35
 90
 65
 45
 35
7/16 – 20
 65
 50
 55
 40
 95
 70
 55
 40
 1/2 – 13
 95
 70
 75
 55
 130
 95
 75
 55
 1/2 – 20
100
 75
 80
 60
 150
110
 80
 60
9/16 – 12
135
100
110
 80
 190
140
110
 80
9/16 – 18
150
110
115
 85
 210
155
115
 85
 5/8 – 11
180
135
150
110
 255
190
150
110
 5/8 – 18
210
155
160
120
 290
215
160
120
 3/4 – 10
325
240
255
190
 460
340
255
190
 3/4 – 16
365
270
285
210
 515
380
285
210
 7/8 – 9
490
360
380
280
 745
550
380
280
 7/8 – 14
530
390
420
310
 825
610
420
310
  1 – 8
720
530
570
420
1100
820
570
420
   1 – 14
800
590
650
480
1200
890
650
480

Last Modified:  25-Jan-2010