27880 Mercruiser WASHER, LOWER SHIFT SHAFT AND CRANK

Improved Rocker Arms
The new rocker arms have a radius roller.The new rocker arms are direct replacement for former rocker arms. The new rocker arms are adaptable back to the first production on C27 and C32 Machine Engines.
Illustration 1 g06405297
(1) Valve rocker arm
(2) Roller
(3) Groove around the roller
Illustration 2 g06405324
(4) New valve roller groove
(5) Former valve roller groove
Table 1
New Reman Group Former Reman Group New Rocker Arm Former Rocker Arm
20R-3319 10R-3483 437-3880 278-1363
20R-3323 10R-6098 437-3879 322-9168
20R-8517 20R-3328 526-1329 437-3870 The change is effective at the factory with engine build date of 01 March 2019.The change is effective on Reman engines and long blocks built on or after 01 March 2019.Note: Reman groups include adjusting screw and nut. The Reference New Assembly does not. Refer to Table 1 for a list of new and former Reman groups.
Illustration 3 g06406961
Typical 384-1367 Valve Rocker Arm
Visual reference chart for base level part identification
(6) New oil path
Illustration 4 g06406965
Visual reference chart for base level part identification
The upper pictures directly below the part numbers show a cut away of the rocker arms, with or without, the oil paths.
The lower pictures show the complete rocker arms for the same part numbers above.
(7) Oil pathsFormer rocker arms included various improvements, the addition of an oil hole for the cam roller outer surface, shown in Illustrations 4.Note: Rocker arm with oil holes will require increased pressure.DLC pins on rocker arms can be reused on new camshafts as long as the camshaft lobes and rollers do not exhibit any signs of scuffing, pitting or skidding failure:1. DLC pins do not undergo break in due to the DLC pins high material hardness (previous generation bronze pin rocker arms underwent break-in and needed to be paired with camshaft, limiting the reusability).2. DLC pins can adapt to any camshaft surface new or reused and DLC pins low friction joint with roller prevents camshaft scuffing and skidding.DLC pins on rocker arms can be reused on new or old camshafts as long as the camshaft lobes and rollers do not exhibit any signs of scuffing, pitting, or skidding. Tracking lines are acceptable and do not indicate camshaft failure and should not affect DLC pin reusability.Progression of Rocker Arms Groups
Refer to Table 2 for the progression of rocker arm part numbers.
Table 2
Progression of Rocker Arm Group C27/C32 ACERT Engine
MEUI (Same for Brake and Non Brake) Part Number Description Nitride Cut Threads P/N Non Nitrided Rolled Threads P/N Isotropic Finish Injector P/N Isotropic Finish Variable P/N Forged Exhaust Rocker Arm P/N Oil Hole Forged Rocker Arms P/N (1) DLC and Oil Hole Forged Rocker Arms P/N (1) DLC and Oil Hole Forged Rocker Arms P/N (2)
MEUI A / LRC (Same for Brake and Non Brake) Arm Gp - Valve Rocker 243-2468 280-8043 301-5349 320-2793 342-6643 392-0066 437-3876 437-3876
Arm Gp - Unit Injector 301-5352 301-5352 301-5352 301-5352
10R-3483 437-3881
20R-3319 437-3881
20R-3319
Injector Arm Assembly 243-2466 278-1363 278-1363 278-1363 278-1363 278-1363 437-3880 437-3880
Injector Arm Part(3) 243-2465 274-5351 274-5351 274-5351 274-5351 274-5351 274-5351 274-5351
Exhaust Arm Gp - Valve Rocker 301-5350 320-2794 320-2794 384-1365
20R-1897 437-3877
20R-3328 524-3708
20R-8517
Exhaust Arm Assembly 259-6122 276-4132 301-5351 320-2795 320-2795 384-1366 437-3870 526-1329
Intake Arm Gp - Valve rocker 301-5354