A-A-91R02
PARTS-SERVICE
Date: Aug. 20, 1985
Model: General Motors
4.153-4.181-6.250 &
GRAM
V8 350 Engines
Engine
SUBJECT: Cylinder Bore Preparation for Re-Ringing General Motors Engines
The top compression rings on General Motors engines are of sandwich type construction with a .010 inch
thick layer of molybdenum on the top and bottom over cast iron in the center. This type ring is designed for
long life with quick and effective seating and minimal wear of the cylinder wall. Improper cylinder bore
preparation will cause rapid ring wear and loss of cylinder compression.
When honing the G.M. engine block after reboring, or when deglazing bores prior to re-ringing, these
instructions should be followed.
1. Use a rigid hone of 280 grit with honing oil. Ensure that stones and pads are clean and free of
foreign matter that could mar cylinder bores.
2. Move hone up and down in bore rapidly, approximately 60 times a minute. This should result in a
cross hatch pattern of 45 to 60 degrees. Hone until bore pattern is uniform throughout bore.
3. After all bores have been honed, use hot water and detergent to wash bores until all traces of
metal particles and honing oil are gone. Dry the bores and swab them out several times with light
engine oil and clean dry cloths.
INTERCHANGEABILITY:
Not affected
PARTS STOCK:
Not affected
SERIAL NUMBER:
Not affected
We reserve the right to make changes in design or add improvements without incur-
ring the obligation to make such changes in equipment previously manufactured.
H6030