This document contains all the dimensions, clearances, and spring pressures for the VIN 7 87 Turbo motor. These are directly from the GM manuals not Chilton's. Now I know that certain engine builders use looser or tighter clearances so don't start a huge thread on how this or that clearance is wrong. Like I said these are from the GM manual. If I were doing a rebuild I would stick with the Factory clearances. How many 140,000 mile cars do we have currently running???
Notes
[h=2]Engine Dimensions and Fits[/h]
[h=3]General[/h]
[h=4]Piston Clearance Limits[/h]
.
Top Land
.046 in. - .056 in
Skirt Top
.0008 in. - .0020 in
Skirt Bottom
.0013 in. - .0035 in
[h=4]Ring Groove Depth[/h]
.
#1 - Compression Ring
.185 in. - .194 in
#2 - Compression Ring
.186 in. - .194 in
#3 - Oil Ring
.188 in. - .196 in
[h=4]Ring Width[/h]
.
#1 - Compression Ring
.077 in. - .078 in
#2 - Compression Ring
.077 in. - .078 in
#3 - Oil Ring
183 in. - .189 in
[h=4]Ring Gap[/h]
.
#1 - Compression Ring
.010 in. - .020 in
#2 - Compression Ring
.010 in. - .020 in
#3 - Oil Ring
.015 in. - .055 in
[h=4]Piston Pin Length[/h]
2.900 in
[h=4]Diameter of Pin[/h]
.9391 in. - .9394 in
[h=4]Pin Clearance in Piston[/h]
.0004 in. - .0007 in
[h=4]Pin Press Fit in Rod[/h]
.0007 in. - .0017 in
[h=4]Pin Direction and Amount Offset in Piston[/h]