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Case 850b 4bt conversion

Z

zswar

New Member
I have a Case 850b that spun a bearing and ended up blowing a decent sized hole in the side of the block. I have a 4bt cummins sitting here and was wondering the cost/ work required to drop it in. I know the newer C's and Ds came with a 4bt so the sizing will be fine. I asssume the bell housing might be different and minor fabrication may be required but the swap seems like it would be worth it rather than tracking down a new block and buying a rebuild kit. Any input helps. TIA
 
T

Tinkerer

Senior Member
The challenge you would have to deal with would be getting the 4bt flywheel to bolt up to the flex plates.
You may need a machine shop to modify the flywheel to get the bolt holes to line up.
Then you may have problem with an out balance assembly after it is bolted together.
That isn't something I would ever do.
Even after doing that the torque convertor to the transmission have to be the same distance like it was with the 336.
I think replacing the 336 with another one is the best option. You could use a 301 to replace it.
 
O

ozarkag

Senior Member
I've done a number of repowers, and while I prefer not too, anytime your swapping to a 4bt it's a good move.
The physical size is the main consideration, and sounds like should work for you. A good machinist can usually solve the flywheel coupling issues. Hayes also will custom build couplings. Might even be able to purchase bell housing or whatever from a C or D.
Seems it's often one of the " little " things, such as intake, exhaust, coolant hoses, throttle that ends up taking a lot of time and ingenuity to get to work.
 
M

MG84

Senior Member
Looked at some specs, in some of the highest power levels case offered the 4T-390 was about the same power as the naturally aspirated 336. However it made that power at a higher rpm. Probably not an ideal swap but it may work.
 
Z

zswar

New Member
Well for anyone that was curious the swap was a success and the dozer is back up and running, some serious custom work had to be done, not a bad way to wrap up a senior project
 
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