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Timing check - timing varies
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Author:  SageRad [ Thu Nov 05, 2015 5:00 am ]
Post subject:  Timing check - timing varies

My '87 Dodge Ram shortbed has been running a bit low on power lately.

I hooked up my timing light and it's generally on the mark but it's varying frmo one strobe to the next, sometimes looks like by a few degrees.

In other words, the mark is not staying totally still.

Is this normal and if not what might be causing it?

Thanks.

Author:  sandy in BC [ Thu Nov 05, 2015 6:25 am ]
Post subject: 

tired timing chain

Author:  DusterIdiot [ Thu Nov 05, 2015 6:29 am ]
Post subject:  Typically it's...

Your timing chain has slack if the mark keeps moving back and forth at a set rpm....

Best way to confirm and check is to pull the distributor cap and pull the spark plugs and roll the crank forward by hand a bit then backwards the same amount and look at the distributor rotor while doing it or have a friend look while you roll the crank....the rotor should immediately move in the direction that the crank is being rolled, if there is any delay (especially when you change directions from forward to backwards) then the timing chain is a little loose and needs to be replaced and the cam set by degreeing not by the "dots" on the gears.

Author:  SageRad [ Thu Nov 05, 2015 7:12 am ]
Post subject: 

Thanks, that makes a ton of sense.

It seems more steady at higher RPMs when i rev it up, and i see the advance as well.

But still not 100% steady.

How big a deal is replcing the timing chain?

thanks.

Author:  SageRad [ Thu Nov 05, 2015 9:06 am ]
Post subject: 

Yes, i did this and it seems to have a lot of play, the rotor is not very "tight" to the crankshaft.

Author:  DadTruck [ Thu Nov 05, 2015 5:39 pm ]
Post subject: 

My 83 D150 had the same issue with an unsteady timing mark when checked with a timing light, swapped out the lean burn ignition for an HEI and the timing mark is rock steady.

Author:  sandy in BC [ Thu Nov 05, 2015 5:51 pm ]
Post subject: 

...you will still need to do the chain,,,,

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