Chrysler Full-Size Trucks 1967-1988 Repair Guide

Valve Seats



Except the 6-251 Gasoline and 6-243 Diesel Engines

See Figure 1

If the valve seat is damaged or burnt and cannot be serviced by refacing, it may be possible to have the seat machined and an insert installed. Consult an automotive machine shop for their advice.

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Fig. Fig. 1: Refacing the valve seats on V8-318 and 360

6-251 Gasoline and 6-243 Diesel

See Figures 2 and 3

Valve seats are replaceable. Special tools are required to remove and install the seats. Considerable care must be exercised when installing the seat inserts. The inserts are installed with a 0.002-0.004 in. (0.05-0.10mm) press fit and must be started in place, true with the counterbore in the block. To install the inserts:

Valve seats are an interference component. This procedure should be done by a reputable machine shop because of the extreme care involved.

  1. You will need to place the inserts in a cool place; one way is the use of dry ice. Approximately 10 minutes would do fine. If this is not available, you may place them in a freezer at least overnight.

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Fig. Fig. 2: Installing the valve seats

  1. Make certain that the block and counterbore are absolutely clean.

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Fig. Fig. 3: Diesel valve face and seat angles

  1. Place the chilled inserts in the counterbore and, using a seat driver, press the insert in until it bottoms.

If the standard insert is too loose, 0.010 in. (0.25mm) oversize are available. If this is necessary, counterbore the block 0.0035 in. (0.088mm) smaller than the insert to be installed. Run the boring tool down until it bottoms out.