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Discussion Starter · #1 ·
Will a 6bt 12v harmonic balancer fit a 4bt. I want to keep my serpentine belt.

By the way, I will be starting a build thread shortly. I have been in the parts gathering mode. I have the 4bta, hx30 turbo from a 2007 (low mount), Ford PS Intercooler form a 2003 (brand new, and lengthened 6 inches to clear chevy radiator support) VE pump is getting treatment now, I finished machining a bellhousing adapter to eliminate the 8 degree offset of the chevy 4bt adapter and also allows installation of a late model GM NV4500. (I'll post pictures in the build thread)
Thanks,
Bob
 

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Will a 6bt 12v harmonic balancer fit a 4bt. I want to keep my serpentine belt.
Yes, and they are usually cheap. The last one I bought was around $25 + shipping.
 

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Discussion Starter · #3 ·
Bob S
Thanks for the info.
Bob B.
 

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Is just the one piece needed, or is there an adapter required? I'm thinking you need adapter too?
 

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What do you gain by swapping to the 6BT harmonic dampener?
 

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Is just the one piece needed, or is there an adapter required? I'm thinking you need adapter too?
I think there may have been a shim on some that were made after 1993 but I haven't had anything that new yet.

What do you gain by swapping to the 6BT harmonic dampener?
The 6BT has a dampener ring and the 4BT is just a plain pulley without a dampener ring attached.
 

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Does it help with anything?

4 cyl cranks are shorter and don't get the "twisties" as bad as long 6 cyl cranks, so I am thinking that is why Cummins left them off of the 4 cyls to begin with.
 

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I believe the main reason they weren't installed is because all 4B- series engines were industrial applications or marine, no real passenger carrying highway vehicles. I guess the thinking was that if you're getting paid to drive it, or use it on water, the vibrations are a non-issue?
 

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The general consensus has been that Cummins designed the 4BT as an agricultural and industrial engine and left it off as a cost saving measure.
 

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The only 4B application that I know of that comes with a damper is the marine version. It's not the same unit that comes with the 6B, It's a add on that bolts to the stock 4B pulley.
 

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The only 4B application that I know of that comes with a damper is the marine version. It's not the same unit that comes with the 6B, It's a add on that bolts to the stock 4B pulley.
Does anyone know the part number for the "add on" that he speeks of???? :idea:
 

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As for the add on damper that's used on the marine version, it is a rare item and the damper for the 6B is so plentiful and cheap why bother?
I added a 6B damper to my Scout 4B to help smooth it out. It didn't do any harm nor did it dampen any more vibes, that I can tell.
 

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I asked about harmonic dampers for 4B's over on the engineering forum and the professonal engineers said one could help with some but not all vibrations. Physically impossible to eliminate a certain order of frequencies and they somewhat explained why. I was too dense to understand "...6th order of magnitude..." but at least got some of what they were saying.

Yes, a 6BT will help, some, but I'm still very curious if the 4B's damper being tuned to a 4 cylinder engine would work better? Don't imagine they're cheap though....
 

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That's just it - - they ~might, maybe~ help with the really high frequencies that cuase a crank to "ring" and eventually crack (if it is the proper tune for that crank), but it won't help with the really low frequncies you feel in your hands, feet or butt.
 
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