4bt 72 Dart

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Nice work

Someone told me that the 4bt is just 2 cylinders removed from the 6bt and that they did not re-time the crankshaft to even out the spacing between the cylinder's firing so there is a tendency to vibrate more?

Is this true ?
 
trapster said:
Nice work

Someone told me that the 4bt is just 2 cylinders removed from the 6bt and that they did not re-time the crankshaft to even out the spacing between the cylinder's firing so there is a tendency to vibrate more?

Is this true ?
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as someone who worked for cummins engineer department and did a 4BT swap into an H2 Hummer, and truck pulled with Cummins for 10 years, that is false.
 
dusterbnb said:
Thanks! I have to admit, the blued metal does look neat, and if I was going to make some kind of rat rod out of it, I would just clear coat it and leave it exposed. But, I'm going to dynomat it, to keep some of the noise down.
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I ran my Duster for awhile with no tunnel, then I ran it awhile with a tunnel and thought that help the noise quite a bit. But now that I’ve put factory padding and a vinyl floor mat in, there’s no way I’d go back to a bare floor! Can’t wait till I get door panels in a headliner and insulation on the ceiling!
 
I'm not an engineer by no means, but the 4bt definitely vibrates a ton at idle, because they are like any other 4 cal that I know of that has 2 cylinders up and 2 down at one moment, an has to make up or can't make up that flat spot that 2 more cylinders at with the 6bt. But, as soon as it comes off idle it smooths out, and you would not even know it vibrates at idle. So, it not bad. It just makes your mirrors vibrate when sitting at a stop light. Or, makes a bread truck/step van sound like it's going to fall apart.

I have thought about rhino lining the floor, as I got that idea form someone on here, and would make cleaning the floor easier. But, I don't know how much it deadens sound, and I don't want it to be like the bread truck and sound like a rattle trap. For an everyday driver, it would get annoying fast.
 
HMM, looking at the pictures of the 2 cranks it look like they just took out the 2 and 5th cylinder and made no attempt to re-time the crankshaft.

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trapster said:
HMM, looking at the pictures of the 2 cranks it look like they just took out the 2 and 5th cylinder and made no attempt to re-time the crankshaft.

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It is different, the lobe angles are slightly different than a 6BT. We're talking fractions of degrees. Irregardless, the 4B, known internally as the B3.9, began design phase in 1980, entered production in 1983. The 4BT came out a couple years later with simply a turbocharger added and the compression ratio modified slightly. The 6BT didn't start design until 1982, entered production in 1984 in industrial application. Therefore the the rumor that a 4B crank is simply a B5.9T, aka 6B crank with lobes cut off and not timed is completely incorrect.
 
Dukeboy….what year 4BT would be the best to look for if someone wanted to put it in say....an old pickup? Sorry for the hijack, but the OP has gotten a lot of people interested in these things! :thumbsup:
 
JDMopar said:
Dukeboy….what year 4BT would be the best to look for if someone wanted to put it in say....an old pickup? Sorry for the hijack, but the OP has gotten a lot of people interested in these things! :thumbsup:
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depends on what you're wanting, if you want the easiest, longest lasting, non-computer controlled 4BT, I'd look for one Pre-1998. Find one with mechanical lift and injection pumps. If you don't want to deal with an aftercooler/intercooler, get a pre 91 4BT.

Same pretty much goes for the 6BT as well. Depending on what pickup, I'd would actually go with a 89-91 5.9BT if you have the room. easier to find and cheaper than a 4BT. and has a very durable mechanical injection pump. They are the lowestest HP rated but can be turned up really easily, can easily make 350 hp, up from the 165hp rating, just by playing with a spring.
 
57 Dodge D100, so not a lot of room for a 6BT. I'd just want it to go down the road with enough power to easily stay with todays traffic, and get good fuel mileage. A turbo and the associated plumbing wouldn't bother me. Would probably use a 4L60 or a 6L90 if I found one from a bread truck with a GM trans and adapter.
 
JDMopar said:
57 Dodge D100, so not a lot of room for a 6BT. I'd just want it to go down the road with enough power to easily stay with todays traffic, and get good fuel mileage. A turbo and the associated plumbing wouldn't bother me. Would probably use a 4L60 or a 6L90 if I found one from a bread truck with a GM trans and adapter.
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sounds good
 
You the VE-pump and the P-pump 4bt just like the 6bt has, and you can do the same mods on them as well. Though, the 4bt tends not to last as long when really cranked up like a 6bt does, but you can get them to 200hp and around 400ftlb and they will run a long time like that.

If room is an issue like mine is. I decided to go with the VE-pump it is a lot smaller and lighter. The P-pump huge and weighs a ton in just the 4cyl one let alone the 6cyl one. But, if you want power the P-pump is the one to go with. They both make power, it's just easier with the P-pump. Also, you can get a fuel plate adjuster for the P-pump. You can adjust the fuel on demand like having a computer one it, but just mechanical instead.

The 4bt also weighs 780 lb with oil in it, just a bit heavier than an iron headed Hemi. Where as the 6bt weighs somewhere north of 900lb. Newer ISB engines (electric engines) weigh over 1,000lb. So, that's something to also think about if you put one in your trunk.

Here are some pics with the differences between the VE-pump and P-pump. P is on top.

IMG_1560.JPG


IMG_2229.JPG
 
Wow....good info! Thanks. I haven't pulled the trigger on the truck yet, but if I don't..... I likely won't ever find another one in as good of shape as this one. I apologize for side tracking the thread. DukeBoy sounds like he knows his stuff about these engines, and you do too. Thanks to both of y'all for the info. :)
 
JDMopar said:
Wow....good info! Thanks. I haven't pulled the trigger on the truck yet, but if I don't..... I likely won't ever find another one in as good of shape as this one. I apologize for side tracking the thread. DukeBoy sounds like he knows his stuff about these engines, and you do too. Thanks to both of y'all for the info. :)
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No problem. I've worked on these engines for over 20 years, as a hobby and a job.

If you have any questions, let me know, glad to help.
 
Your welcome, and no problem with the questions. I am glad to try and help with what ever I can. I am no expert by any means, but I have read a lot and worked as Diesel mechanic for 12 years now. The site (4bt swaps) has a ton of info and there is probably someone that has done your project already, to get helpful info from and ideas.
 
For some following this thread and where it has it's side comments- I stuffed a Gen 1 4BT/Turbo 400 into a Wrangler. Dana 60 and 70 narrowed, 4.56:1 Gears. Pulling a 3500lb trailer and running the A/C all the time I got 21mpg every tankful.
 
Well I have not posted in a while, because I assembled the front end and set it on the ground to push it outside so I could wash the car. While moving it I found out how badly the angles where off because of swapping it to front steer. It would work it you drag raced it, but when turning it drug the outer tire terribly. I would probably be going through steer tires every month. So, it took some thinking and I broke down and bought a HDK (HemiDenny) K-frame. It is absolutely beautiful, and how the pieces are what would say Keyed together is amazing. I started installing it and will hopefully get it installed the rest of the way next week. Thought I didn’t want to buy an aftermarket K-frame, I’m glad I did. I know it will be safe to drive. But, now I have to remake the motor mounts that go in the frame.

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Looks like you have some good components to do your build on. I'm wondering what and whose coil overs you'll be using. That engine is a hefty little nugget.
 
dusterbnb said:
I would like to put one in some kind of half ton Dodge, and put a military trailer bed on it. There are several motor mount kits that would make it easy to do, since it has a frame.
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Clearly, I'm late to this party but let me jump on the bandwagon of Very Neat Build. This will be so cool.

I've been in trucking my whole life, and I'm a huge fan of diesels and torque. To reference the above, I'm following your build for ideas to drop a diesel into my D150. It's an 82, currently a slant/4-speed OD/8-1/4 with a bad engine. A diesel would turn this into a powerhouse with good mileage and a stick. What's not to like?

A photo of the truck on the way home.

coming home 3.jpg
 
halfafish said:
Clearly, I'm late to this party but let me jump on the bandwagon of Very Neat Build. This will be so cool.

I've been in trucking my whole life, and I'm a huge fan of diesels and torque. To reference the above, I'm following your build for ideas to drop a diesel into my D150. It's an 82, currently a slant/4-speed OD/8-1/4 with a bad engine. A diesel would turn this into a powerhouse with good mileage and a stick. What's not to like?

A photo of the truck on the way home.

View attachment 1715250978
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You're upgrading the 833 OD to an NP 435 or a NV4500 I hope? A stock Cummins torque will shred an OD833
 
thepaintguy said:
Looks like you have some good components to do your build on. I'm wondering what and whose coil overs you'll be using. That engine is a hefty little nugget.
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I think they are QA1 shocks, and talking to Denny, he said that I should probably go with 400# springs.
 
halfafish said:
Clearly, I'm late to this party but let me jump on the bandwagon of Very Neat Build. This will be so cool.

I've been in trucking my whole life, and I'm a huge fan of diesels and torque. To reference the above, I'm following your build for ideas to drop a diesel into my D150. It's an 82, currently a slant/4-speed OD/8-1/4 with a bad engine. A diesel would turn this into a powerhouse with good mileage and a stick. What's not to like?

A photo of the truck on the way home.

View attachment 1715250978
Click to expand...

Yeah, a NV4500 would be great in that. I wish I was able to fit the one I had in better. That shifter would of been right into the a/c ducting.

Whether you use a 4bt or a 6bt, it would be great in that truck. You can find VE-pump 6bt pretty cheap, especially compared to a 4bt, though the 4bt would be lighter.
 
JDMopar said:
Dukeboy….what year 4BT would be the best to look for if someone wanted to put it in say....an old pickup? Sorry for the hijack, but the OP has gotten a lot of people interested in these things! :thumbsup:
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Isn't there a newer model 4BT that has a balance shaft which helps a lot with the shaky idle?
 
dusterbnb said:
I think they are QA1 shocks, and talking to Denny, he said that I should probably go with 400# springs.
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hmm seems a tad light. the spring rates on my coil overs for my 440 are 375#. That 4B weighs substantially more. That said, I'd go with what Denny says for now, can always swap them out easily later.
 
toolmanmike said:
Isn't there a newer model 4BT that has a balance shaft which helps a lot with the shaky idle?
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the newer 4B would be that. But its computer controlled and to swap it to a mechanical would require swapping the entire front gear drive and cover.
 
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