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The Gentleman's Express: Tech-Tips from the JIOC

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Replacement Timing Chain

Author: Ms N C Rhoden

After reading Mike Lotwis’ urgent recommendation, I had my mechanic change the cam drive chain assembly by switching to the two-row roller timing chain with metal sprockets. The installed set was Cloyes P/N 9-2104. Cost was $108 with another $175 for labor, and while he was at it, I had him replace the water pump and all drive belts.

Direct Connection also has these Cloyes assemblies available under the following part numbers:

3-bolt cam sprocketP4120263
1-bolt cam sprocketP4120264

With all of these installations, we have to discard the oil slinger (Chrysler #2899530) as the crank drive sprocket is so much wider due to the double- row chain.

How do we know when our Interceptor needs attention to its timing chain? The normal life span for the cam gear is 100000 plus miles. Many do not make it quite that far, often resulting in bent valves and push rods. What are the signs of impending failure? Some of the telltale signs may be vacuum loss, difficulty in starting, occasional backfiring, difficulty in tuning the engine and if it seems like only four or five pistons are kicking in and the others kick in later, or the unique symptom of loss of braking after 4 or 5 hard stops.

The following are offered as suggestions for checking the timing chain: compression test, vacuum test, check the distributor advance on the scope and, if all else fails, pull the timing chain cover.

A surefire way to check whether the chain and gear are worn:

Tools 1-1/4" x 1/2" drive socket
Extra long breaker bar or extension 1/2" drive
Screwdriver, slotted type

The job is best performed with ignition off. Remove the distributor cap and, standing on the right-hand side of the car, put the socket with extension on the large crankshaft nut. Work this back and forth which in turn works the crankshaft until you can feel the cam gear engaging. Now watch the rotor in the distributor and note how far you have to move the extension bar before the rotor moves. If left to right and reverse movement is excessive, there is play in the timing chain. You will have to do this a few times until you get the feel of it.

Once you get the feel, you’ll then be able to tell if the movement is excessive. Remember that there is some free movement to begin with and that will be amplified by the length of the breaker bar or extension, but if you start with the bar lying on one fender and end up lying across the car with the bar on the other fender before the slack is taken up and the rotor finally moves, that definitely is EXCESSIVE, and a sure sign that you are in need of a new timing chain and gear set.

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Contents copyright 2008, 2009 - Jody F. Kerr

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