Cylinder Head - Add to Measuring Warpage & Mating

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Number: 90-352-6A

Section: 6A

Date: October 1990

Corporate Bulletin No.: 036108


Subject:
ENGINE MECHANICAL - CYLINDER HEAD


Model and Year:
1990 GEO STORM


TO: ALL CHEVROLET DEALERS

Add this procedure to the other measuring procedure on page 6A1-17 and 6A2-18 in the CYLINDER HEAD portion of the ENGINE MECHANICAL SECTIONS 6A1 and 6A2 in the 1990 GEO Storm Service Manual (ST371-90).

MEASURE

Tool Required:

J 26900-9

Cylinder head mating surfaces for flatness. Using a precision straightedge and a J 26900-9 feeler gage, measure the cylinder head along diagonal lines where it contacts the exhaust and intake manifolds, and its engine block contact surface. If warpage along any axis exceeds 0.2 mm (0.0078 inch) the cylinder head must be reground; if warpage along any axis exceeds 0.4 mm (0.0158 inch) the cylinder head must be replaced.





Figure 1 - Inspecting for Warpage DOHC Engine Shown, SOHC Similar.





Figure 2 - Cylinder Head Mating Surfaces DOHC Engine Shown, SOHC Similar.