Re: timing chain

[Matt Haas <mhaas@xxxxxxx>]

Jay,

At 107,000 miles, it's probably stretched enough where it could stand to be 
replaced but letting it go isn't going to hurt anything since AMC 6's 
aren't interference engines (unlike dang near everything with a timing 
belt). A quick look through the engine section of my TSM didn't show any 
specification for checking chain stretch (of course, there may be something 
there that I just didn't see). There may be something in the archives about 
checking this. I think this topic came up in the spring.

A quick check is to pull the spark plugs, remove the distributor cap, 
rotate the engine in one direction about a quarter turn to take up all the 
chain slack and then rotate it in the opposite direction. When you rotate 
in the opposite direction from the first, the rotor should start to move 
within a few degrees of crank movement. If there's a lot of stretch, you 
may feel the engine get noticeably harder to turn when the slop is taken up 
and you start moving the valve train. A new chain on an engine with new 
bearings (wear in the cam and crank bearings causes more slack) doesn't 
have much slop at all in it. I didn't measure how quickly the rotor was 
able to change directions when I replaced my distributor recently but it 
did start moving almost immediately (I have about 6,000 miles on my rebuild).

Unless I was having performance and/or driveability problems that couldn't 
be solved with a tune up and/or fixing vacuum leaks, I'd just leave it 
alone. The worst thing that's likely to happen is that you'll need a tow 
home. Also, if the stock cam gear has plastic teeth on it, those typically 
fail (long before chain stretch is an issue) when the engine is started 
which further reduces the chance for damage.

Matt

At 09:17 PM 11/6/2004 -0500, you wrote:
> I have 107k miles on my 66 Amereican w/232 engine. At about what mileage 
> should I condsider changing the chain & gear?
>
> Jay in FL.

mhaas@xxxxxxx
Cincinnati, OH
http://www.mattsoldcars.com
1966 Rambler Rebel
1968 Rambler American sedan
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