Official Cummins 4BT Swap Thread for CJ-7's - Page 4 -
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post #46 of 320 Old 08-25-2008, 03:52 PM
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Originally Posted by BigTorqueCJ View Post
Harder on the ball joints?
yes, as stated i have a six cylinder in there now and a 4BT would be several hundred pounds heavier than that. im assuming the dana 44 only has one part number for the upper and lower balljoint, from your reply. if i want heavier duty balljoints i have to upgrade the whole axle, to say a 60? what did the CJ come with originally, those equipped with the six that is?

Originally Posted by BigTorqueCJ View Post
I have noticed NO difference in handling as far as steering/cornering or durability issues are concerned. (...) beware: The engine swap turns your CJ into a whole new beast!
okay, now im confused. will my jeep handle differently or not?

Originally Posted by BigTorqueCJ View Post
If you don't have Wrangler springs on the front of your CJ yet, I would start there.
youre referring to the YJ wrangler leaf springs, correct?

thanks for the reply. ~D

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post #47 of 320 Old 08-25-2008, 07:27 PM Thread Starter
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The CJ-7 came with a Dana 30 front axle regardless of the engine. I put in a shortened Wagoneer D44 in my Jeep, due to busting the ring and pinion in my D30. I don't know if the D44 only has one part number for the balljoints: I've never replaced them. I recommend a Dana 60 in the front only if you plan to run larger than 35in tires.

The Jeep with a Cummins will handle differently as far as: shift points, boost, and off-idle tree-stump pulling torque. Steering, cornering and general road handling/stability has not changed for me. When I say, "The CJ is a whole new beast" I'm referring to the fact I had to kind of learn how the engine power-transfer reacts with my drivetrain and the road. Since the stock 4BT engine limits revs at 2500 and you now have a turbo with charge air boost, it is a different kind of driving from the gassers I used to run.

Yes, one of the best things any CJ owner can do is put YJ Wrangler leaf springs in the front to replace the narrow CJ springs.

Sold the BMW to afford Jeep parts.
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post #48 of 320 Old 09-03-2008, 09:47 AM
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the YJ springs are there any mods that need to be done with the or do the just bolt right in place?

Currently a twigdet learning the ways of the Gear Head PLEASE be patient...
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post #49 of 320 Old 09-24-2008, 08:36 AM
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You have to weld in larger perches for the shackles and and springs to sit on, you are moving up from a 2 inch spring to a 2.5 inch spring.

2005 TJ X: 2" RE spacer lift, 32"x11.5" tires, 1.25" Zone body lift, Curry Antirock sway bar.
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post #50 of 320 Old 11-07-2008, 12:05 PM
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Shopping list?

('84 4.2 CJ-7)
After researching, I have decided this is a conversion I plan to do. Time and the wif...err...I mean, uh, um, money, ya, that it, money; however, will likely prevent me for really getting started till sometime after mid-next year. My two goals for the swap are going diesel and at the same time I would like to re-wire the electrical, simplifying as much as I can.

With that in mind, I would like to start working on some of the necessary upgrades and begin collecting the needed parts.

1. What mods should I be looking at doing to me Jeep that can be done now and which will become necessary/recommended when I do the swap?
2. What hard to find/expensive parts should I be on the lookout for and begin collecting?
3. Re-manufactured? Rebuilt? Used? Any suggestions on where's a good place to acquire a good value (price/quality=value) 4BT and how's best to determine the that I'm getting a good value?
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post #51 of 320 Old 11-27-2008, 05:18 PM
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i am a little short but for those of you interested if you in the jersey area take a look

Currently a twigdet learning the ways of the Gear Head PLEASE be patient...
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post #52 of 320 Old 12-05-2008, 10:00 AM Thread Starter
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Hey Raccroc,

It's time to convert that 4.2L to a 3.9. I hope for your sake you are able to follow through with your plans.

1. I think you should have a moderate lift to get the front axle away from the oil pan of the 4BT. Maybe you already have that, I don't know. I have a Spring-over set-up with Front Wrangler Old Man Emu springs. I have a winch and the engine make the springs just about flat.

2. Parts to look out for now and possible start collecting (I collected my parts over about 6 months). I guess a lot depends on what transmission you want to use, but here is my list: all available from 2 generation Dodge ram diesels.

Flywheel housing / Bellhousing / Flywheel / Clutch / Hydroboost / Hoses for hydroboost / Clutch slave cylinder

3. I bought my 4BT off of e-Bay, it had 87k miles on it, came from a Frito-lay truck, drove 150 miles to get it, it runs like new. I think you will have to watch e-bay for several months and decide for yourself what a good deal is. I haven't been looking for them since I got mine. I do think that unless you want to spend a ton a money on a rebuild, you should just get a running engine with the lowest miles you can find.

Sold the BMW to afford Jeep parts.
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post #53 of 320 Old 01-09-2009, 12:31 PM
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This may not be a great question, but which vehicles originally came with this motor? Where would someone start looking for a used one or one in a yard?

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post #54 of 320 Old 01-27-2009, 02:54 AM Thread Starter
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This motor was originally produced as an industrial application. It was soon later used in the automotive world and most popularized as the "Cummins Re-power Program" that put Cummins 4BT engines into Step Vans that had tired 6.2 GM diesels. There are thousands of these out there, so it isn’t too difficult to find one. Frito-Lay must have done a ton of these, because it seems that their trucks are where the bulk of these are coming from. This engine can also be found in some Ford E350 cube vans, Chevy/GMC P30/P3500 step vans, and Case 580 Tractors.

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post #55 of 320 Old 01-27-2009, 07:42 AM
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Tips/trick/advice from a Diesel-holic

On that note- you're gonna want to AVOID any 4bt in a generator application, as the injector pump will not work for a OTR (over the road) application. The injection pump on the gens. was meant to pick up a load and adjust the idle accordingly.

I got my 4bt from a Ford chassis. The differences in the Ford/Chevy apps. are as follows (not all-inclusive, and not set in stone, but this is what I have seen):
1: The Ford's usually have a T-19 4 spd
2:The Chev's usually have an auto (turbo 400 I think)
3:The Ford's have an exhaust manifold that puts the turbo to the rear, mounted low (down).
4: The Chevy's mount theirs center and high (up).
5: The older (not sure of cut-off year) 4bt's have a rotory injection pump.
6:The newer (years??) 4bt's use an inline injection pump. (look at a 24v Cummins and you'll see an example of an inline pump).
7:Most Ford's do not use a power steering pump.
8:Alot of Chevy's do use a p-steering pump (this is important, as they are hard, not impossible to find- IF you do not live on the East coast -I know, weird...)
9:The Ford's use a vaccuum pump (driven off of the belts) to power the brake booster.
10: Most Chevy's have the desirable 'biscuit style' engine mounts. These mounts are fluid filled and really dampen out the 4bt's vibes. (think older Volvo style mounts)
11: Some Chevy versions are after-cooled. This is really easy to spot. On top of the driver's side of the engine, over the intake manifold, there is a long, tall box the tubo dumps it's charged air into.
12: Most Ford's use a vertical style oil filter. (It is almost exactly like the regular 6bt in Dodge trucks)
13: The majority of Chevy's use a verticle oil filter mount (messier @ oil change time)

Keep in mind:
The 4bt/6bt's are 'modular', as stated previously. That said, you are liable to run into a mix/match in anything.
In addition to E-bay, look at Craigslist. I got my whole truck for $1,900.00. I was able to sell the aluminum body as scrap for $1,000, the steel frame for $200, and the rear axle for $100. So, my 4bt, T-19 and wiring harness ended up costing me $600.00.

BEFORE you buy check:
The engine!! There are ALOT of crapped out Cummins out there ppl. are trying to sell. I have seen many that aren't worth the steel they are cast from.

A seller will tell you that these engines are 'bullet proof' or 'indestructible'. As any one knows, if it moves, it will wear out. Generally, these Cummins will last many 100's of thousands of miles, with the proper mait.

After 250k-ish you should check it for (let it warm up first...):
-Smoke from the turbo-a little black under power and throttle blips is normal. Spewing black indicates the turbo is shot. White smoke=engine needs attention. Probably the head gasket is gone (destroyed).

Always check for the normal-Oil leakes- these motors are usually ALWAYS filthy. You are looking for fresh oil, or dripping oil.
Nefarious rattles- it's a diesel, so it's gonna rattle. A rod knock or faulty injector is pretty easy to spot.

Let the engine get up to op. temp. with a squirt bottle, spray the exhaust manifold, near to where it meets the head. Don't soak it, it may crack. You are looking for a 'cool' exhaust port. If the water doesn't evap. as quickly on one port, likely a cylinder is dead, or the valve(s) is/are dead.

ALL Cummins use THE SAME SAE fly wheel pattern on the block. ALL OTR apps. use adapters to allow the use of Ford/Chevy/Dodge trannies (this doesn't include machinery or generators-likely they have some kind of SAE transmission). Use this to your advantage when re-powering your ride. Keep in mind the starter/input shaft/clutch req'ts.

Diesel autos and gas autos use different torque converters and valve bodies.

These engines were meant as medium duty industrial engines-that means maintenance is pretty easy, and you can even rebuild the engine in the vehicle. Replacement parts are pretty easy to come by.

Not ALL 6bt/4bt parts are interchangable.

-the oil cooler on the 6bt is too efficent for the 4bt
-only the injectors from the 1st generation- I think '89-'92 12valve's- will fit the 4bt.
-the turbo's are interchangable, but you need to know what you are doing-a bigger turbo DOES NOT EQUAL MORE POWER!!
-in diesels, the more fuel you give it, the more power you get. BUT it must be balanced with more air.
-EGT's/oil level/quality. Exhaust gas temperatures (EGT's) and the engine oil are the life and death of any diesel. Get an EGT gauge. For safety's sake, I wouldn't exceed 1050-1100 deg. on a 4bt. The 6bt's can go higher. Aluminum melts at 1200 deg. sustained. -enough said- Oil--make sure you have enough, and the right quality. Diesels use the oil to help trap soot. If your oil breaks down, so do you.

-On the EGT issue. If you are having trouble keeping the EGT's down you can:
-increase air flow to the engine
-decrease fuel to the engine
-cool the airflow (intercooler, water/meth injection...)
-ensure your engine is tuned correctly (lean diesels run cool, rich diesels run hot)

FINALLY: I am not a diesel mechanic. These are simply tips/tricks/knowledge I have gathered in my travels. I absolutely LOVE Cummins and have devoted alot of time learning about these great engines! I am on my 3rd Cummins re-power. Take the above for what it's worth, if not, no biggie. Also, diesel-holics (you KNOW who you are) if you see anything that is in error, please feel free to correct me- I am never to old to learn!!

1948 CJ3A, In the process of a full rebuild.
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post #56 of 320 Old 05-16-2009, 09:26 AM
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I know this is resurecting an older thread, but I have quick question for BigTorqueCJ or 4BTCJ3. You mentioned that basically majority of parts are interchangable from a 4BT to 6BT, and you used the NV4500 because you had already swapped it in. Instead of swapping out the input shaft and houseing etc etc. Couldn't someone simply take a Manual Tranny and T-case from a first Gen Dodge Diesel truck and swap it in? Would this basically bolt straight up? Would a stock clutch etc for this same truck work? Would the flywheel on the 4BT still need to be swapped out?

Thanks for all the info BTW. Oh and another question, I know that the "subtle" difference between the Chev and Ford Applications can be a headache, but I have heard that the Chev version is the better way to go especially because of the exhaust and turbo placement.

Lastly other than switching your tank to diesel did you have to do anything different with the fuel system, (manual or electric fuel pump, changes to ?). And how was the wiring of the beast, big pain or? Any tips on parts to be sure come with a 4BT when looking for one (i.e. make sure it has ....)?

Thanks again
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post #57 of 320 Old 05-18-2009, 07:59 PM Thread Starter
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I think you could attach any of the first 3 generation Dodge transmission set-ups. If I remember correctly: The first gen would have the Getrag transmission, the second would have NV4500 and the third would have NV4500 or NV5600.
I think the T19 that came behind 4BT's has too small of a clutch and flywheel to attach the 'dodge' transmissions to.

You do want a 4BT from an automotive set-up (not an industrial set-up).
You will most likely want a 4BT with the turbo outlet on the bottom, it's a much closer set-up to most stock applications.

There is a manual fuel pump on the side of the engine. For my CJ I just dumped the gas out of my tank, blew out the fuel lines and attached the supply to the pump and return line to the tube on the side of the engine.

Unlike most, I love automotive wiring. The 4BT was the easiest engine compartment to wire up. I thought that I touched on it in my write up but all you need to do is:
1. Attach the fuel shut-off solenoid to a key-on power wire (your old "ignition" wire).
2. Attach the alternator wires
3. Attach the starter wires
Piece of cake!

I bought a complete running 4BT with 85k on it. I would recommend this way. It gets expensive if your engine is missing a few parts.

Good luck!

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post #58 of 320 Old 07-17-2009, 10:52 PM
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awesome thread, i was thinking about this swap, i have a smallish chevy in mine. i like the idea of the turbo, FUEL mileage, and the monster torque, which will get you to top speed just the same (if your top speed is 45mph). the info you and others have provided will be very helpful, thanks.

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post #59 of 320 Old 09-08-2009, 04:56 PM
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I just started my build. I bougt a bread truck out of New Hampshire for 1000 bucks. It has a th400 chevy trans behind it. My CJ has/had a chevy 350 in it so I am wondering if because the 4bt was mated to a chevy trans in the bread truck and my jeep had a chevy 350 is the bellhousing adapter the same for a chevy auto as it is for a manual? I know a lot about the cummins engines as I had a 95 dodge 12valve diesel making 537hp and 1106ft/lbs to the wheels and ran 12 second quarter miles, but as far as the 4bts going into a jeep I am pretty clueless. My 4bt has the VE rotary pump unfortunately but I plan to run my HX35 turbo that was stock on my dodge with a set of lucas Prince OF Darkness injectors, a upgraded fuel pin, and a 3200rpm governor spring. This should bring my hp to about 160-170 and about 425ft/lbs of torque. Sorry for rambling but I am very excited about this build.
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post #60 of 320 Old 09-08-2009, 08:49 PM
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I have spent a lot of time tuning and messing around with these engines in my 04 3rd gen Ram, Construction equipment, and other industrial applications and if you are serious about making big numbers change the front timing cover to accept the inline bosch p pump. It makes a world of difference. Yes the rotary pump can make power but like the Ram guys are aware the 6bt with the P7100 pump is legendary for fuel delivery. I just finished building a 6bt 24v engine that was originally equipped with the VP44 pump and replaced the timing cover to accept the p7100. With 24 valves and huge fuel delivery it romps (plus twins help). I would be more interested in doing this if Cummins had ever produced a 16v head for the 4bt. Maybe they had but I have never seen one.
To seriously support the power try to find a small intercooler (construction equipment salvage yards have all kinds of compact ones) and or run a water methanol injection system (windshield washer fluid works great) to reduce the boosted air temp. My snow system makes great power and keeps EGT's in line under long hard pulls.
Sorry for rambling but Cummins builds an awesome engine!!!!

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