Needing some assistance from the group (Search for NHC250 or Big Cam)

[TripleSteel]

I need some help locating a nhc250 or a suitable replacement Big cam for a M939A1.
Has someone documented the exact changes needed for a big cam?
I have read through several of the threads here, but might have missed something.
I am located in Missouri but can travel for the right motor

Long story short the motor is one of the unlucky "rebuilds" missing a wrist pin clip.
The current motor has been trashed when the piston came apart and rod went through the liner.

700 hours on the meter.

 

[Crf450x]

Have you tried looking for a local heavy duty junkyard? Some of them still fool with 855s and some don’t.

 

[Lukes_deuce]

If you have facebook, there is a really good group dedicated just to the 855 Cummins. They have lots of parts and motors for sale. Search for 855 Cummins enthusiasts

 

[simp5782]

If you are working the truck the Big Cam is going to smoke the transmission.

If it's not a vented air block then just drop a liner in it and go.

 

[TripleSteel]

The damage extends into the oring seat area for the liner in the block. i would have to get block welded and machined to keep coolant out of the pan.
crank is questionable
valve train is unknown but the top half of the piston got hammered flush with the head when it came apart.
I was thinking i would be money ahead to source another engine and overhaul.

@simp5782 if i sourced a 300hp or less Big cam would it play nice with the allison.
i do use the truck to pull a lowboy and dozer around (52k total weight on the two )

 

[Steelreaper80]

Put an 8.3 in!!!

I like my 8.3.......