Re: IML: 73 440

["Pete Engel" <peter.engel@xxxxxxxxxxx>]

Tim,

The B/RB engines are most definitely NON-interference engines.  A chain can
break or a sprocket strip while you're cruising down the highway and the
engine will simply stop without damaging the valves or piston tops.

That's almost never how the failure happens though.  Stress on the camshaft
sprocket teeth (they are what fail) is highest during engine starting.  So
what happens is that while you're driving, the last bits of nylon teeth
break off the aluminum sprocket but the chain is held outward by centrifugal
force and continues to drive the cam.  Then, when you shut the engine off,
the chain sags and hangs loose around the crankshaft sprocket.  When you try
to restart there's not enough "bite" between the crankshaft sprocket and the
chain so the crank spins but the cam stays put.

You should be replacing the timing set at 100k miles anyway since that is
about the time that the nylon will start to break off the cam sprocket.
Once the nylon starts to break off the shedding process accelerate rapidly.

I've replaced a bunch of timing sets due to the "it ran fine when I shut it
off but now it won't start and it cranks funny" phone call.

Here's a sprocket from a 69 or 70 Charger 440.  110k miles.  Replaced the
timing set and off the owner went.

http://bos-engel.com/imperial/sprocket.JPG

Here's a shot of timing chain slack on my 66 New Yorker.  97k miles and I
replaced it before it left me sit.

http://bos-engel.com/MML/slack.jpg

Pete in PA

Date: Mon, 12 Feb 2007 07:40:25 -0800 (PST)
From: Tim Durrer <tdkd99@xxxxxxxxx>
Subject: IML: 73 440
Reply-To: mailing-list@xxxxxxxxxxxxxxxx
Does anyone know for certain if a 73 440 is an
interference engine or not?

I still debating on a timing chain and gear
replacement on my 73 with 101,000 miles. I recall the
small block Chrysler engines would basically self
destruct if the cam sprocket stripped.

Tim Durrer
73 LeBaron Blue Sky




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