Table 4-1. Engine fits, tolerances, and wear limits-continued

TM 5-4320-234-34

Table 4-1. Engine fits, tolerances, and wear limits - Continued

Manufacturer's

Design clearances

dimensions in

in inches

Allowable

Component points of measurement

inches

wear or

clearance

Min

Max.

Min.

Max

Ring groove width (cont.)

2nd and 3rd

0.1275

0.1285

0.1305

(0.3187 cm)

(0.3212 cm)

(0.3262 cm)

4th

0.2520

0.2530

0.2550

(0.6300 cm)

(0.6325 cm)

(0.6375 cm)

Cylinder bore diameter

3.4375

3.4395

3.4475

(8.5937 cm)

(8.5987 cm)

(8.6187 cm)

Piston fit in bore. Check by pull

5 to 10 lb

on 1/2-inch wide x 0.003-inch

(2.250 to 4.500 kg)

feeler gage

Piston rings

Width

No. 1

0.1230

0.1240

0.1210

(0.3075 cm)

(0.3100 cm)

(0.3025 cm)

No. 2 and 3

0.1230

0.1240

0.1210

(0.3075 cm)

(0.3100 cm)

(0.3025 cm)

No. 4

0.2485

0.2490

0.2465

(0.6212 cm)

(0.6225 cm)

(0.6162 cm)

Gap

No. 1

0.007

0.017

(0.0175 cm)

(0.0425 cm)

No. 2 and 3

0.007

0.017

(0.0175 cm)

(0.0425 cm)

No. 4

0.007

0.017

(0.0175 cm)

(0.0425 cm)

Side clearance

No. 1

0.0035

0.0050

(0.0087 cm)

(0.0125 cm)

No. 2 and 3

0.0035

0.0055

(0.0087 cm)

(0.0137 cm)

No. 4

0.0030

0.0045

(0.0075 cm)

(0.0112 cm)

Piston pin

Length

2.805

2.815

(7.012 cm)

(7.037 cm)

Pin diameter

0.8591

0.8593

0.8588

(2.1477 cm)

(2.1482 cm)

Piston pin bushing diameter

0.8595

0.8597

0.8067

(2.1487 cm)

(2.1492 cm)

Piston pin fit in piston

Light push

Piston pin fit in rod

0.0002

0.0006

(0.0005 cm)

(0.0015 cm)

Valve spring

Weight required to compress to

47 lb

53 lb

42 lb

1-45/64 in. (valve closed)

(21.15 kg)

(23.85 kg)

(18.19 kg)

Weight required to compress to

96 lb

104 lb

86 lb

1-27/64 in. (valve open)

(43.20 kg)

(46.80 kg)

(34.40 kg)

Section II. ENGINE REPAIR AND OVERHAUL

NOTE

parts if necessary (para 3-22). Remove

You can do some engine repair with the

accessories from the engine as required.

engine in the engine housing. More

4-3. Cylinder Head

a. Removal. Remove the cylinder head and gasket

extensive repair will require removal of

as shown in figure 4-1. When removing the cylinder

the engine from the housing. Major

head screws, loosen each a small increment until all are

repair or overhaul requires that the

started. This will help prevent cylinder head distortion.

engine be mounted on an engine

Repeat for several more small increments until all are

overhaul stand.

Remove the engine

loose.

housing (TM 5-4320-234-12, para 4-19).

Remove the engine from its mounting

4-3