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Discussion Starter #1
Starting this build thread off here to start getting more advice and information as I get ever closer to the point of no return. I'm too cheap to buy a newer Dodge and I like me some old iron :flipoff2:

Starting with a 1972 J4600 Truck. Currently has a AMC360/TH400/Dana20 in it with a closed knuckle 44 front and non FF 60 rear with 4.10's. This is how it came from the factory. Engine and tranny have roughly 10K on them since a rebuild. The truck will haul anything and move anything, maybe not fast, but it moves it. Truck currently gets 9 mpg or so empty and 7-8 while towing (at 60mph) :(.

Plans for the build:

6BT Cummins mated to a RoadRanger RTO-6610 10 speed transmission. Divorced NP205. Ford Super Duty axles (D60 and 10.50). Going this route to mainly increase milage, hoping to double it at least. Second reason is to make towing easier. I hate the TH400 that is in the truck. There is so much power lost during towing it is not even funny. (tranny is fresh, I just hate slush boxes) I am choosing to go with the RTO-6610 because I have read too many stories about the NV's and Getregs having problems with sheared off gears and twisted input shafts etc. I also wanted to be able to split my gears from a standard 5-6 speed tranny. The RTO provides this ability and keeps all the gears in one box. I looked into under/over drive aux boxes and didn't like what I found in relation to holding up to a 6BT.


A big concern was being able to keep up road speed and not blow up the engine over time (and cause another "$7000 mistake" :laughing: ) The RTO has a .8 overdrive gear on the top end. Being able to do at least 70mph on the road with out over revving was a goal. The old drive line combo could do 90 mph, but the engine was nearing red line. I will be going with 3.73's in the axles, 33in tires, combined with the .8 overdrive this puts the rpms @65mph around 1950ish. 2130rpms at 70 mph. I little higher than great, but it is a start. The tires I have now on the truck are 33's, so the next set may be 34's or 35's to get a better top end out of it. (35's @ 65mph = 1860 rpms :smokin: )

Plans are to start by removing the old drive line and swapping the axles first. Then move into stuffing 10lbs of shit into a 5lb hole. I have a 6BT from a 1994 L7000 that I parted out (see my sig for parts :grinpimp:) with 65K on the clock. Jus broke in. Will be getting the RTO and the 205 shortly, as they are coming from a yard that is building them. Plans are the KDP fix and clean and paint the engine. Mate it to the tranny and get it in the hole. Once in I will be using the "heavy duty truck mounts" that are already on the engine. This is a mid drive line mount on the SAE#2 clutch housing and the front engine mount.

One of many questions I have thus far that I am still trying to figure out:

Brakes to stop this beast. Was looking at going with a master cylinder/hydroboost setup from a super duty. Is the proportioning valve built into this unit or no? I figured this would be the best set up to take care of the disc front and back axles I have and it was all used by Ford anyways... The PS pump/res that I have now will be plenty to handle the extra usage. Will prolly run a cooler for it too.


and for the picture lovers

The Donor..



There's a Cummins in there somewhere....



The J4600

 

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I'd rather have the ford to be honest. Aside from needing some new tires, it looks to be a nice truck. Wouldn't really want to have to deal with beefing up a 40 year old 3/4 ton frame for a Cummins/RR either.

Although I've seen 5.9's in F700 and F800's, I'd kind of figure an L7 would at least have an 8.3?
 

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Discussion Starter #6
Your going to put that 10spd tranny in that pickup?

I have got to see this.
They've been stuffed into late model trucks. It's not as big as you think. Nicknamed the "baby 10".

You in New York?
Yeah...?

I'd rather have the ford to be honest. Aside from needing some new tires, it looks to be a nice truck. Wouldn't really want to have to deal with beefing up a 40 year old 3/4 ton frame for a Cummins/RR either.

Although I've seen 5.9's in F700 and F800's, I'd kind of figure an L7 would at least have an 8.3?
Truck was a nice truck. Needed Kingpins and tires to be perfect. It's in pieces now though. It was cheaper than any clapped out dodge with 200K on it that I could find. The L series came with MANY different engine options. This one jus happened to have a 5.9L. You also need a CDL to drive the Ford... and all the paperwork and taxes and inspections and bs that goes with running a HDT in NY.

Will that beast fit under the hood or run without it?
Yes it will fit. Been done many a time before. Only concern I have for space allocation right now is the intercooler. Working on that though.
 

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This should be a good read. I assume you will need to hack the Jeep body and fire wall up a bit?
Take lots of pictures!
 

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check out 4btswaps. A guy on there did a J20 with either a 4bt or 6bt. It was a good build thread.

Also there is a guy in the local club that had a 10 speed or so in his 98ish Dodge 1 ton. He had to cut the sh*t out of his floor. and reroute the exhaust to outside the frame rail and add air to sift it. That is after he blew up 2 nv 4500's.

Good luck, I put a 6bt into a 89 F350. It's the little things that kill ya...
 

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Also there is a guy in the local club that had a 10 speed or so in his 98ish Dodge 1 ton. He had to cut the sh*t out of his floor. and reroute the exhaust to outside the frame rail and add air to sift it. That is after he blew up 2 nv 4500's.
He (or another guy with a similar rig) had a build thread here on pirate. Very inspirational! It opened my mind to real transmissions.
:D
 

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Discussion Starter #14
This should be a good read. I assume you will need to hack the Jeep body and fire wall up a bit?
Take lots of pictures!
I know the engine will fit in the hole with no cutting, the tranny on the other hand... that will be a see as I go deal. Pictures will be plentiful. I plan on starting all this at the end of next week.

this will be tits.

I have an un-natural lust for your J-truck.
Easy meow. :flipoff2:

check out 4btswaps. A guy on there did a J20 with either a 4bt or 6bt. It was a good build thread.

Also there is a guy in the local club that had a 10 speed or so in his 98ish Dodge 1 ton. He had to cut the sh*t out of his floor. and reroute the exhaust to outside the frame rail and add air to sift it. That is after he blew up 2 nv 4500's.

Good luck, I put a 6bt into a 89 F350. It's the little things that kill ya...
I have been reading other J series cummins swaps for about a year now. I am hoping I can get all my ducks in a row from studying the other builds.

If you were closer I would see what you wanted for the 360.
Sorry, it already has been assigned a home. My father's '75 waggy with a 4 spd behind it :smokin:
 

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I think the trans and bell is gonna require way more fitment work than the engine will by a long shot.
Travis..
 

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6BT Cummins mated to a RoadRanger RTO-6610 10 speed transmission. Divorced NP205. Ford Super Duty axles (D60 and 10.50). Going this route to mainly increase milage, hoping to double it at least. Second reason is to make towing easier. I hate the TH400 that is in the truck. There is so much power lost during towing it is not even funny. (tranny is fresh, I just hate slush boxes)
Sub-frickin'-scribed. :smokin:


I will be going with 3.73's in the axles, 33in tires, combined with the .8 overdrive this puts the rpms @65mph around 1950ish. 2130rpms at 70 mph. I little higher than great, but it is a start. The tires I have now on the truck are 33's, so the next set may be 34's or 35's to get a better top end out of it. (35's @ 65mph = 1860 rpms :smokin: )
You did your homework. :grinpimp:
 

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Discussion Starter #20
I think the trans and bell is gonna require way more fitment work than the engine will by a long shot.
Travis..
Duly noted.

Me thinks this is gonna be an awesome build!! :) ya could check out the idea of using the stock bell/flywheel housing and all out of the dodge and have a clutch built and not have to hack the body up, just my .02 :) Keep it up!
RTO won't mate to a Dodge bell, you need an SAE#2 clutch housing to get the RTO to fit.

You did your homework. :grinpimp:
Yes Sir :D Don't wanna do this twice.

:idea: Cut your shifter down a bit so it's not as tall as Mindless' :)
Well that takes the classy right outa it :flipoff2:
 
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