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Discussion Starter #1
I've been told that one of the 4B series engines had a crankshaft harmonic damper. Does anybody have the part number available? Thanks!

JimmieD
 

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you was told wrong. there is a balance assembly for 2400.00 bucks that goes on the bottom of the engine, inside the oil pan driven off the crank. i just priced the setup last week.
bob
 

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Discussion Starter #3
Thanks, Bob. Yes, that's the twin balance shaft assembly. Complicated and pricey. Works though.
 

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If you're talking about the one that goes on the front of the crank I've got one for a 6BT, bolts right on to the 4BT. Pulley is integral with the dampener, I can get part # if you want.
 

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1989 Jeep Wagoneer, 360v8, 727, stock for now,
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The 6B crankshaft harmonic damper will bolt on to the 4B, But are they required, no. The only 4B I know of that has a harmonic damper on is the 250hp marine version. This unit attaches to the face of the existing pully in the parts book I have.
I put a 6B harmonic damper on my 4B for the ease of adding the magnets for a tach.
 

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Discussion Starter #8
The only damper that will really 'work' on both 6B & 4B is a fluid type. The orders of crank vibrations are entirely different and vertical forces are different also. I've heard from several people that the 6B damper is an improvement, but it's not a cure as such. For what I'm after I think it might be a huge improvement. Possibly the QSB 4.5L damper would be better.
 

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52Wrench, But does it WORK on the 4BT? Bolting up, and functioning are two different things....DAMHIK.


RW
Define "Functioning ". If you mean will it make it as smooth as a 6BT, hell no. Will it make it smoother than without one? probably.
 

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Discussion Starter #10
That tach option is a biggie! That alone is enough reason to use the 6B damper and put up with some vibration here and there. What's involved with the rest of the bits and pieces to get a tach working? Expensive?
 

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Tach Option

I purchased a GMC and haven't had the time to tear into it yet. But it has a non-working tach on the dash. I figured it was cable driven and would be an easy swap into my repower truck. Am I wrong or is it just you wanted wires other than the drive cable?
 

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That tach option is a biggie! That alone is enough reason to use the 6B damper and put up with some vibration here and there. What's involved with the rest of the bits and pieces to get a tach working? Expensive?
Get your pdf copy of the Iisspro.catalog On page 14 is a listing for tachs that use the magnetic sensors. Don't know the price.
 

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Discussion Starter #13
Thanks for the tips and link.

The only thing my engine had for tach drive is the 3rd alternator spade connection. There's no provision for a cable driven tach that I've heard of. The 6BT type tach with a sensor is supposed to be a little more accurate than the 4BT's alternator impulse tach so for me that would be preferred. Don't know how much the rest of it would cost, or if there's even an interface to use 6B tach on 4B.
 
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