LBZ to LMM swap??

Jun 1, 2020
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I put the wrong oil for the weather in my 2006 duramax and now has what the mechanic thinks is a rod bearing going. I am looking at options to get her back to work. I found an LMM with 56k miles for $2k. Does anyone know what it would take to put the LMM in my truck. If it matters I have larger injectors, turbo & all the stuff to go with those upgrades on my current motor.

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gmduramax

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Jun 12, 2008
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I appreciate your response. Pardon my ignorance, so what would need to me customized to put it in my rig?

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Nothing just use those parts from your LBZ motor and put them on the LMM motor. There might be a couple things I’m forgetting but it’s all interchangeable
 

2004LB7

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Is it the LMM injectors that are slightly larger in diameter then the LBZ so you have to use thicker O rings on an LBZ injector when installed in an LMM head?
 
Jun 1, 2020
37
1
8
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Nothing just use those parts from your LBZ motor and put them on the LMM motor. There might be a couple things I’m forgetting but it’s all interchangeable
I just went to the bigger injectors & turbo & the stronger head bolts a year ago. Would I lose all that stuff or would most of that bolt in?

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2004LB7

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If you have studs then you should be able to move them over. Turbo, injectors should be a direct swap with the o rings I mentioned above
 
Jun 1, 2020
37
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If you have studs then you should be able to move them over. Turbo, injectors should be a direct swap with the o rings I mentioned above
I appreciate your help. This is my rig for the business I started & was just about to expand to doing hotshot loads too but now I'm parked not making any money.
So sounds like the mechanic should be able make it work semi easily. Different o rings for the injectors like you said. Will I be using the heads from the LMM with the stronger studs I put in my old motor?

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gmduramax

Shits broke
Jun 12, 2008
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Nor cal
Is it the LMM injectors that are slightly larger in diameter then the LBZ so you have to use thicker O rings on an LBZ injector when installed in an LMM head?
That was LLY and LBZ
LBZ and LMM injectors are the same dimensions only the LMM has 6 hole instead of 7. The connector on the LBZ has an extra ridge on it you can cut off if you want to run LBZ injectors with an LMM harness.
 
Jun 1, 2020
37
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That was LLY and LBZ
LBZ and LMM injectors are the same dimensions only the LMM has 6 hole instead of 7. The connector on the LBZ has an extra ridge on it you can cut off if you want to run LBZ injectors with an LMM harness.
Awesome! I really appreciate everyone's help. You guys saved my a$$

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Jun 1, 2020
37
1
8
5
That was LLY and LBZ
LBZ and LMM injectors are the same dimensions only the LMM has 6 hole instead of 7. The connector on the LBZ has an extra ridge on it you can cut off if you want to run LBZ injectors with an LMM harness.
Does this mean there is no difference??



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Bdsankey

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Does this mean there is no difference??



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Swap your harness, injectors, and turbo onto the LMM motor.

If you did studs in your engine it may not be a bad idea to bite the bullet and do a quick head gasket job while that LMM engine is on the ground. It's more money but then you're done once and for all. You also can stud it one-by-one meaning remove one OEM head bolt and replace it with your head stud, torque it, repeat until all of them are replaced. When doing this I like to take them to 100ft-lbs then follow ARP's torque sequence for the last pull to 125ft-lbs.


As for the injector plugs, many aftermarket companies make parts that fit multiple years. Think of it this way, do you want to stock 3 injector plug SKUs to cover 04.5-10 or just 1? That's why they do it. It drives manufacturing price down and profits up.
 
Last edited:
Jun 1, 2020
37
1
8
5
Swap your harness, injectors, and turbo onto the LMM motor.

If you did studs in your engine it may not be a bad idea to bite the bullet and do a quick head gasket job while that LMM engine is on the ground. It's more money but then you're done once and for all. You also can stud it one-by-one meaning remove one OEM head bolt and replace it with your head stud, torque it, repeat until all of them are replaced. When doing this I like to take them to 100ft-lbs then follow ARP's torque sequence for the last pull to 125ft-lbs.
LMM heads were just redone so not on the motor.
I was told the plugs were different & the diameter of the injectors were a different diameter. However when I went to a few different links to order the LBZ & LMM were the same part numbers

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2004LB7

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LMM heads were just redone so not on the motor.
I was told the plugs were different & the diameter of the injectors were a different diameter. However when I went to a few different links to order the LBZ & LMM were the same part numbers

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It's been clarified above that the LBZ and LMM injectors are the same size. Plug has a little tab that keeps them from being swapped unless removed
 
Jun 1, 2020
37
1
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It's been clarified above that the LBZ and LMM injectors are the same size. Plug has a little tab that keeps them from being swapped unless removed
I'm using my injectors on the same wiring harness. I'm just using the long block & heads so everything should be good then I guess

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Bdsankey

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LMM heads were just redone so not on the motor.
I was told the plugs were different & the diameter of the injectors were a different diameter. However when I went to a few different links to order the LBZ & LMM were the same part numbers

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Use your LBZ injectors and your LBZ harness, then there's nothing to worry about. LBZ and LMM bodies are the same dimension.