Vibration Problem

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Jax340Dart

Jax340Dart

Well-Known Member
Joined
Aug 28, 2015
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Location
Albion Pa
Hello Fellas,, This is the first time I posted a problem so please bear with me. I thought I would ask the Mopar Gurus if anyone could help. I bought the car last fall with a blown head gasket and numerous other "rigged" problems. Anyway I have a vibration starting at 3000 RPM. At first I thought it was around 60 MPH but tried it in park and it is still there. It has a 340 cast only balancer on it and a 10235 flex plate. The problem is the serial numbers on the block are: partial 34 then 0 03028069 thats all I can make out. The best I figured is its a Nov 1968 block. That means it has a forged crank right? Unless the crank was changed, it has the wrong balancer on it. Does this seem right to you all? Im late for church so I have to hurry. Thanks for any help
Bob
 
If it's been "rigged" in a variety of ways, after so many years, it may of may not have a forged crank in it now. But, yes, the balancer and flex plate are for a cast crank and 340's came with forged cranks through somewhere in the '72 model year.

Might be a cast or forged 318 crank that wasn't rebalanced! I don't have the casting/forged numbers handy.

Make sure the converter doesn't have any balance weights on it. (i.e.: cast crank 340 or 360 application.)

Best way to tell is to drop the oil pan to check out the crank. The link shows a 440 crank, but the visual features to ID if it's cast or forged is the same.

http://www.moparts.org/Tech/Archive/bb/img/crankshaftid.jpg
 
Thanks for the reply. I did check the converter and there are no weights. I will take the belts off sometime today and try that. I was going to check everything else I could think of before taking off the pan. Although that should probably be the FIRST thing I did !!.
 
Thanks, I will try that too. Gotta put brakes and rotors on all four corners today on the Grand Cherokee so it will have to be later on in the week
 
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