The amount of twisting force
(torque) on a bolt or screw is normally measured by
the use of a torque wrench.
The correct tightening of bolts
is one of the most singularly important operations done
when repairing an engine or component.
Correct torque can eliminate
deformation of mating surfaces, cylinder head to the
block, intake and exhaust manifold to the block, main
bearing caps to the block, rod caps to the connecting
rod to mention a few of the very critical areas. It
can also eliminate bolt breakage, thread stripping,
water and oil leaks.
Virtually every bolt and screw
on an engine or component has a torque specification
for correct tightening. It is imperative that the manufacturer's
recommendation be followed for correct tightening sequence
and tightness to eliminate problems created by bolts
and screws being too tight or too loose.
S.A.E. BOLT GRADE
AND RECOMMENDED TORQUE CHART
S.A.E.
GRADE |
1
or 2 |
5 |
6 |
8 |
RECOMMENDED
FOR COMPETITION AND CRITICAL USE |
 |
 |
 |
 |
 |
| 1/4
DIA |
5
Ft. lbs |
7
Ft. lbs |
10
Ft. Ibs |
10.5
Ft. lbs |
11
Ft. lbs |
| 5/16 |
9 |
14 |
19 |
22 |
24 |
| 3/8 |
15 |
25 |
34 |
37 |
40 |
| 7/16 |
24 |
40 |
55 |
60 |
65 |
| 1/2 |
37 |
60 |
85 |
92 |
97 |
| 9/16 |
53 |
88 |
120 |
132 |
141 |
| 5/8 |
74 |
120 |
167 |
180 |
192 |
| 3/4 |
120 |
220 |
280 |
286 |
316 |
| 7/8 |
190 |
302 |
440 |
473 |
503 |
| 1 |
282 |
466 |
660 |
714 |
771 |
(P21-22)
|
