From: D O (dohe69@hotmail.com)
Date: Sun May 23 2004 - 10:46:58 PDT
I second B-man's recommendation on the worn timing chain/gearset as a
possible cause.
I seem to remember a general rule of thumb spec being a max of 7? degrees of
crankshaft rotation without distributor movement, but cannot remember
exactly. Same idea, different method of measurement.
>From: "Brian Redick" <B-Man@wesnet.com>
>To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
>Subject: Re: [MV] M880 erratic idle
>Date: Sun, 23 May 2004 08:36:00 -0400
>
>Your problem is most likely a worn out timing chain and gearset. It is
>recommended that if the original gear and chain is still installed, that it
>be changed at 70,000 due to excessive wear. If the timing chain is sloppy
>enough it will cause your timing mark to move all over the place at idle.
>
>One easy way to test for excessive slop in the chain and gearset is to pop
>off the distributor cap, exposing the rotor button. Place a long breaker
>bar and appropriate sized socket on the crank balancer bolt in lower
>pulley.
>Move the crankshaft back and forth in small increments until the rotor
>button begins to turn. Take notice of how much rotation is necessary to
>begin moving the rotor button. If the crank pulley rotates more than 1/8
>to
>1/4" inch it will cause your valve timing and ignition timing to move
>around.
>
>I have had many many Mopar vehicles over the years and none of them had
>ever
>had a worn out distributor, so I doubt the distributor is the problem. My
>M882 is a 1976 with 86,000 miles and absolutely nothing had been replaced
>on
>the engine with exception of a new carb and new heater hoses and belts.
>Needless to say, my timing chain and gear needs replaced as well!!!
>
>Brian
>M882 Ohio
>
>-----Original Message-----
>From: Military Vehicles Mailing List [mailto:mil-veh@mil-veh.org] On Behalf
>Of Vernon Tuck
>Sent: Saturday, May 22, 2004 11:21 PM
>To: Military Vehicles Mailing List
>Subject: Re: [MV] M880 erratic idle
>
>I don't know anything at all about your particular critter. However, a
>worn
>out distributor can be the source of erratic timing readings.
>Eelliptically
>worn bushings are one possible culprit. Weak springs on a mechanical
>advance and/or gooey dirt and grime inside there are another.
>
>VT
>
>"I have a 1977 Dodge M880 with a 318 V-8 and a 2 barrel Carter Carb just
>added in December. TM specs the timining at 2 degrees before TDC. That is
>adjusted the best I could however the idle is erratic and has been for a
>while.While shooting the timing gun, the mark varied between the 2 degree
>set point and 5 degrees.I have been unable to establish a steady enough
>idle
>at this setting to get ti any closer. Origianblly the timing was upwards of
>10 degrees before TDC at this setting the idle wasn't so erratic, but
>didn't
>match any available spec for this motor. Once the truck is at any setting
>above idle then there is no problem at all. Also, I discovered that the
>fuel
>filter is only about half full while running, is this a problem or normal
>operation?"
>
>
>
>
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>
>
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