TM-9-2815-220-34 Direct Support Manual for AVDS-1790-2C and AVDS-1790-2D Engines Download

dcribed In (a) and (b) below. (a) Use a fine mill file to remove sharp corners of broken head fine. Do not remove more metal than necsary  pruce a smꝏthly blended edge on the damaged fin. (b) Depth of any blended fin must not be ls . than < percent of its original depth. When blended fin is ls than 2 percent. of original depth, replace cylinder assembly. (2) St and irueru. Replace damaged, bent or stripped studs as deacrid in paragraph 8-88 and Cylinder Standard Stud Identification (table 3-14). Replace defective helicaloil inserts as described in · paragraph 8-39. e. Valve Rker Arm Covers. (1) Repair or replace damaged parts. Replace cylinder assembly when valve rker arm cover is cracked or has deep scratches or nicks on the mating surface. Replace cylinder when cover damaged can- not be removed by polishing wit1 crocus cloth I dipped in dry-cleanfog solvent (P-D-680, Type II). (2) Replace cylinder assembly when valve rker cover dœs not conform to Jimita specified in the repair standards (table 3-13). Replace damaged screw thread inserts as instructed in paragraph 3-39. Replace cracked adjusting covers. Remove minor · nicks, burs, or scratches from mating surface with crocus cloth dipped in d ry-cJeaJ1ing solvent I (P-D-680, Type II). f. Valve Rocker Arm. (1) Replace valve rker arms (= and P, fig. 3- 1Z) when cracked or worn or if the valve rker am1 roller and bushing are worn or damaged. (2) Replace adjusting screw (34) when threads are stripp or damaged or when screw binds in rker arm. Replace adjusting screw when swivel pad dœs not rotate frly on screw. 8· Valve Rocker Arm St Aembliea. (1) Replace cracked or deeply scored rker arm shaft aembli (14 and 31, fig. 8-1Z). (2) Replace rker arm shafts that do not n· form  limits specified in the repair standards (table 8-13). h. Valve, Spring•, Spring Retainers and Rotor1. (1) Valves. {a) Discard valves (2 and 8, fig. 8-1Z) which do not conform to limits specified in repair standards (table 8-18). Discard valves having warp, crack, pit or bued fac. Discard valves having badly pitted, seor, scratched ste or lking grꝏv. TM 9-2815-220-34 (b) Reface slightly pitted or burned valves that do not have  of ntact  limita specified in fire 3-1c. Discard valves that cannot be refaced  these limits. Check valve length from seat conct to tip of stem after grinding, as shown i n figure 8-1c. Discard valve if length is not within limits specified, (2) Valve springs. Replace springs (8, 9, and 10, fig. 8-1Z) when worn, cracked or otherwise damad. Replace springs that do not conform to limits specified in repair standards (table 3-18). (3) Valve spring retainers, valve rotors, and valve l�. (a} Replace upper intake a nd exhaust valve spring retainers (11 and X, fig. 8-1Z) and valve spring seat (7) when cracked or wo.· (b) Replace valve rotors (%) when inner s- tion dœs not rotate freely or when assembly is worn or cracked. Replace valve lk spring retainers (,) when worn or cracked. 3· 73. Assembly a. Cylinders. (1) Install intake valve (8, fig, 8-1Z) and exhaust valve (2) in their respective guides in cylinder (6). Hold valves in pition and place the cylinder on valve removing and inserting stand (fig. 8-1V). (2) Install the exhaust valve rotor (87, fig. 8-1V) outer, intermediate and inner springs (8, 9, and 10), and exhaust valve spring upper retainer (X) over the exhaust valve stem as shown in figure 8-1X. Insll the lower inke valve spring seat (7) outer, in- termediate and inner springs (8, 9, and 10), and upper intake valve spring retainer (11) over the intake stem in ·the same manner. Compresi valve springs and in- stall valve locks following instructions which ac- company figure 3-2. (a) Position the valve lifter assembly Part No. 8761585 over the valve springs and retainers and cure in position with four 6/16 x 1-3/8 bolts and 6/1 in. flat washers. (b) Compress valve springs and retainers with screws and install two valve lk spring retainers (,) in the grꝏve of each valve stem. Release valve spring comprsion. Remove valve lifter assembly Part No. 8761:5 from cylinder and remove cylinder from stand. . . (c) Check vaJves for leakage by pJacing cylinder on its side with intake or exhaust port up and fiJlli1g valve porl with dry-cleaning solvent (P-D-680, Type II) and observing valve seat area for Ouicl leakage. Change 3 3·107