The official 6bt conversion thread

[averagef250]

Look what I just bought: http://cgi.ebay.com/ebaymotors/ws/eBayI ... 043&rd=1,1

$3600 to my door! I happen to know a guy that has a clapped out 6.5 turbo and bad 4L80E in a '97 K2500. I called him up and said $6500 for a 4BTA and good 4L80E with cummins controller installed. I had a check in my hand 30 minutes later!

I'll have to swap the 2wd 4l80E over to a 4x4 tailshaft, but $2500 in labor ain't bad for under a weeks work.

[71PA_Highboy]

I will be about 15 miles from that seller later this week if anyone wants me to stop in and say Hi or check anything out.

Let me know,

Eric

[averagef250]

He seams like a real nice guy and I've spoken with other's that have done business with him before. Probably no need to check anything out for me anyway.

If a guy bought a 4BTA, 4L80E and TCM controller seperately you'd be atleast double the $3050 selling price!

[averagef250]

I have a feeling there will be a surplus of them soon with all the breadvans that just sold on dovebid. That breadvan in Sacremento is a heck of a deal.

[averagef250]

I agree 100%. The new overpowered, overweight pickups are rediculous.

If a guy was liquid enough, he could probably capitalize on the situation. Buy up every 4BT breadvan you could find and buy up every nice old truck that'd make a good swap candidate. Start an assembly line swapping them in and I'd be willing to bet you could get enough for them to make it profitable.

I don't think I'd have a problem selling my '71 in the $12K and up range. With good marketing I'd bet the same truck could fetch $20K or better as a realistic alternative to buying a new diesel pile of junk.

There are companies popping up all over the country offering 4BT conversions. Individuals are shelling out $20K and more for 4BT swaps.

[71PA_Highboy]

OK,

So I have read this entire thread about half a dozen times, and I still have some questions (mainly for Dustin ).

I USE my truck... a ton of gravel in the bed or towing my Early Bronco behind it or pulling stumps (literally) or 2 tons of landshaping rocks to my GF's house 2 hours away.

Currently I have a 360/435/4.11 combo. With a 4bt am I going to see at least equal performance in these tasks as I do with the 360 or am I going to be wishing for more performance? What are the REAL LIFE experiences you have had and how did the 4BT measure up?

TIA,

Eric

[Mooosman]

After having gone through this whole thread a couple times, and lurking over at 4btswaps.com for a few weeks, I can say that this idea is making me wish I wasn't building my hot-rod 300-6. While the 300 I'm building is going to be a fun little motor, it is going to be pretty grumpy when putting around town (248/254@.050 cam and 11:1 Compression).

Well, putting around town is where I do most of my driving! And the Cummins would seem to be an ideal engine to put in there for that purpose.

I think I could knock down over 30mpg with my 72 2wd, SWB with power nothing and the ZF 5 speed, too! I think the rated weight for this thing is like 3500 lbs or so, so it should get pretty decent mileage.

Anyone want to trade a complete 4bt setup for a 300+ horse 300-6??

Nick,
May be making a calssifieds ad soon!

[averagef250]

I'd say an intercooled 4BT with a larger turbo would best the meanest 360.

The meanest 300 horse cranked up 4BTA I've had the opportunity to drive seams to match the pulling power of a purpose built 400+ inch long stroke big block, but does get twice or better the mileage doing the same job.

If you want big pulling power go with the 12 valve 6BT. The problem with the 6BT is it's too much power for everything else under the truck. T-case, drivelines, axles, etc all need beefed. That and it doesn't really fit.

[Mooosman]

Not looking for pulling power, just for a daily driver that will get decent mileage. Not that I'm complaining now, as the original 240/3 speed/3.70 gear combo gets 21 mpg highway right now!

30+mpg would be nice with a 4BT, though!

Nick

P.S. Do you have any pics of a 4BT mated to a 2wd ZF? Can I use the stock 72 crossmember?

[averagef250]

I'd recommend the Mazda tranny for a light truck DD. It's got better ratios than the gas 2wd ZF. You'd have to modify the crossmember. The M5R2 gives you 5 real forward gears. You get 4 and granny with the ZF unless you go with a diesel ZF or put diesel ZF guts in a gas 2wd case.

The stock 4BT's got way more power than any 240 I've ever driven, but all the 240's I've driven have been flat worn out.

[Mooosman]

Yeah, this 240 has 155,000 on it, so it's not exactly at the top of its game, either. z

Which Mazda tranny do I use? I'm assuming 1/2 ton with the small block pattern? Did the 4.9/5.0/5.8 all use the same ratios?

90% of my driving is with an empty bed or very light loads. The thing will almost never see any real loads. Hell, I bet the original 3 speed stick would stand up fine for a while!

Nick,
Thinking diesel...

[averagef250]

You're right on there...The Mazda M5R2 was used in the 1/2 ton and light 3/4 ton trucks with a six or small block. They all had the same ratios.

For an old 2wd truck the one to find is the 88 to 91 model because it has the speedo drive stuff.

370 gears will probably be too low depending on tire size. With 31"s I'd say 3.25's or so and smaller tires 300 gears. It's best to gear for 1700 RPM at cruising speed with the 4BT.

[Mooosman]

I was figuring on a gear change. With my current gearing and tire height, I top out around 60mph and 3000 rpm.

Not exactly cruising rpm for a diesel!

Nick

[averagef250]

I got another complete 4BT from the friend that was driving my '71 when it died a couple days ago. I detailed it up nice today and painted it up black (not a fan of cummins beige). I also bought the "366" 3200 RPM governor spring to install. I've worked on a good number of diesels, but never actually gotten to the innards of an injector pump before. I was a little hesitant at first and looked through all kinds of instructions for the 366 spring install on the web, even printed off a 13 page step by step procedure.

Well, once I took the first 4 screws out I started to realize how darn simple these IP's are inside and threw the instructions in the trash.

The whole spring swap detailed in 13 pages of BS takes 12mm, 17mm wrenches, a 5MM allen wrench, a thin steel rule and 5 minutes for a braindead monkey with one arm tied behind his back to complete.

A VE pump makes a quadrajet look like cutting edge rocket science.

[mljjones67]

Pretty simple then huh? How much did the spring cost ya?? I am planning on flying out this weekend to get those bread trucks. Should be an adventure.