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Discussion Starter #1
Hey guys, Just looking for some direction on the new truck I bought. It's a 91 intercooled b5.9-160hp stock motor with 250000mi on it and Im going to put it in my 72 chevy c20. Im going take it down to the block and start fresh with it. I would like to get ALL of the hp I can out of it. Any help would be great because Im new to the cummins and new to the forum. thanks
 

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What are your plans with the truck. That makes a big decision on what you can do with the engine.

Is this going to be a daily driver??

Are you going to be towing a lot and heavy?

Are you going to be sled pulling?

Is the engine going to be IC'd?

What trans are you going to be using. "Don't say turbo 400 eather".
 

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Discussion Starter #3
Im going to use the truck as a show, Drag race, maby pull once. Its a 2wd and I would like to find a allison 1000 auto if it will work.
 

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The problem with the ally 1K is finding someone that will program the controller for it. Getting it bolted to the engine isn't a problem. There is an aftermarket controller made for it. It is for the 5 spd model only.

The floor pan might be another issure. An SAE #3 adapter is going to be a real tight fit. The chevy adapaters used on the 4BT's in the bread trucks most of the time had the engines setting at about a 5 degree angle for the engine to clear the cover assy. So in a straight up install of the engine that would tilt the trans at 5 degrees.

I have owned a 5ea 68 to 72, C30's over a 20 year period. Those trucks I know inside and out.

As far as droping a B series in that is easy. You can use eather a second gen frame mount or 1st gen engine mounts and fab the frame mounts yourself. The heater box is a problem. The turbo wants to set right where it is. If you use a vintage air unit that would cure your problem. I have seen a swap where the guy just moved the heater core into the main heater box inside the cab. Then he cut the outer box to clear the turbo.

The swap I saw into a 71 C10 he had used the Dodge auto. It fit the tunnel with no issues.
 

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Discussion Starter #5
I have also thougth about using the old 4 speed but dont know if it will hold or can be made to hold.
 

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Your going to need an OD trans at least. That C20 is most likely 4:10 gears. Without an OD you would top out against the governors around 50 MPH.

That SM465 will not last for long behind a 6BT. It isn't rated for the torque the cummins puts out.
 

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If the donor truck is a 91 intercooled then its a 91.5, and should have the 518 4 speed transmission, which has OD. Now, its a decent unit, and can be built to be better. Also, it is possible to upgrade it to a lock up style unit, but it may be less expensive to locate a 47RH transmission from a 94-95 dodge. If you can't find one, then upgrading the 518 would be best. The 518 can be built to perform, but not having a lock up converter is its downfall.

The A1000 is a good idea, but very spendy and time consuming.
 

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Discussion Starter #8
yes its a 1991.5, the thing is that the tranny in it needs to be rebuilt. My 72 chevy has a 4 speed manual in it but will it hold the extra hp?
 

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Its not the HP that will kill that SM465. It is the torque. The cummins puts out about twice the torque of any gas engines of that era. The SM465 was border line with a 396 in those year trucks. Thats why most of the BB trucks were auto's. The BB's you did find with a stick never had a posi in them. It was chevy's safety net on trans/rear axle warrenty repairs.
 
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