Piston/Pin/Ring Specifications

1990 Chevrolet Step Van 5.7 K, Automatic, 3L80/M40SECTION Piston/Pin/Ring Specifications
PISTONS, PINS & RINGS SPECIFICATIONS

Application In. (mm)
Piston Clearance
Bohn Pistons
Bores No. 1-6 .0035-.0045 (.089-.115)
Bores No. 7 & 8 .0040-.0050 (.102-.128)
Zollner Pistons
Bores No. 1-6 .0044-.0054 (.112-.138)
Bores No. 7 & 8 .0049-.0059 (.125-.151)
Pins
Diameter 1.2203-1.2206 (30.996-31.004)
Piston Fit Slip Fit
Rod Fit .00031-.00121 (.0081-.0309)
Rings
No. 1
End Gap .012-.023 (.30-.55)
Side Clearance .0030-.0070 (.076-.178)
No. 2
End Gap .029-.039 (.75-1.00)
Side Clearance .0015-.0031 (.039-.080)
No. 3 (Oil)
End Gap .010-.020 (.25-.51)
Side Clearance .0016-.0038 (.040-.096)
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.