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Valve Adjustment on the Chrysler/Plymouth/Dodge Slant Six

based on a letter
from Iver Krogh

[Later slant six engines do not require valve adjustment.]

Iver Krogh sent in an optional method to adjust valves on the slant six engine, without having to run the engine with the valve covers off. Allpar has not tested this method and is not responsible for its use.

Start by marking the harmonic balancer around the edge, so the marks you put on and the timing mark divide it in thirds. Warm up the engine.


Shut the engine, take off the valve cover, and turn the engine until the timing mark is lined up properly, and the front two rocker arms are a little loose. That puts the first cylinder at top-dead-center. You may want to mark the intake or exhaust valves; the valve opposite the exhaust runner is the exhaust valve, while the valve across from the intake runner is the intake valve.

Usually, Chrysler recommends 0.010” for the intake and 0.020” for the exhaust. Some suggest leaving pre-1973 slant sixes, which may not have hardened valve seats, a little looser — 0.012” and 0.022” — to avoid burning. Now adjust the rocker arm screw so there is the correct amount of play (e.g. 0.010”) between the valve tip and the rocker arm, using feeler gauges.

Turn the engine in the normal rotation direction, until the first of your new marks lines up with the timing tab; then adjust the next cylinder in the firing order (1-5-3-6-2-4). Once you’ve done all six cylinders, clean the valve cover and head, and install the cover with a new gasket.

Most people adjust the engine while hot, as shown in the video above.

Also see: the slant six engine

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