6BT rod knocker
 

http://www.speedhunters.com/2015/09/...rtr-ford-f150/

Ever since I read about this truck it has gotten me to want a off road tuned truck, but I want a old Chevy crew. As I get closer to having my new car paid down enough to get rid of it starts looking like reality.

The basic plan was a warmed up big block, and overdrive trans. Make some longer A arm's, air bags at all 4 corners, 4 link, and uniballs for durability. Toss on some AT tires, and enjoy. Nothing hardcore, but a truck that works well for the stuff I really due.

So a week ago I drove a 89's Dodge with a 6BT, and a few basic mods. Wow it was quick, and got me wanting one. Or atleast seriously considering one heavily.

The engine weighs 1200 or so pounds, and the planned Big Block weighs under 700 after planned mods.

So for you guys have done the mod how much did it affect handling or is it livable with proper set up. I do not tow much, and I drive my personal vehicle less then 7500 miles a year as I have a company van. So I can easily live with a big block, and it's down sides on mpg. So the 500+ extra pounds on the nose is my concern.

Re: 6BT rod knocker
 

Your biggest concern will be the frame. I used to be involved in Cummins swaps and had a 6BT in an '88 Chevy. Most guys end up heavily boxing the frame, at the very least, do the front half. The good swap kits include a new crossmember to help strengthen things up as well. The weight isn't a lot to worry about with the proper spring setup.

Re: 6BT rod knocker
 

Or you could find a 4bt its the 4 cylinder version of the 6bt,Its 700 lbs and can make half the power a 6bt can.

Re: 6BT rod knocker
 

A 4bt might be a good option if you really want to go diesel. They can be built to put out some pretty serious numbers and would cut down the weight a fair amount.

Re: 6BT rod knocker
 

I have thought about the 4BT before after I rode in a truck that was so equiped. The truck was a 72 C20 with a 4L80, and 3.42 gears. He tweaked the truck for mpg while keeping occasional load capacity. He usually got 25-27 hwy driving about 70mph.

My only concern is that it does not put out the kind of torque a 6BT can do reliably. So going into a big crew likely is the wrong idea unless mpg was my goal. As I would have to up its performance to expensive levels.

Re: 6BT rod knocker
 

The other thing you have to consider with the 4BT is actually finding one. They don't come up for sale often, and you could buy a 6BT and hop it up for the price of just finding a 4BT.

Re: 6BT rod knocker
 

At a minimum I'd want a 3/4 ton and preferably a 1 ton if you're running that heavy of an engine. I guess all the crew cabs are 3/4 ton and up so that's less of a problem.

Re: 6BT rod knocker
 

I prefer EFI big block. Vortec 454 and 4L80E are east to find and usually not very expensive. My current tow rig is a 99 GMC Suburban with a Vortec 454 that I bought for 2k. if mileage isn't a concern it's a good option, gas engines are cheap to maintain.

Re: 6BT rod knocker
 

As long as I use proper tires with plenty of pressure,
my Suburban with the 6BT up front handles fine. Stock frame has held up just fine. I drive mine quite a few miles each year so the better mileage has paid for itself. Where the 6BT shines is heavy towing, fuel economy and simplicity. It has been by far the most reliable rig I have ever owned.

Re: 6BT rod knocker
 

Talk to member 1774btcrew he has a 4bt in a crew cab truck,A 4bt can make some big power for its size but won't pull the insane numbers a 12 valve can.And the biggest downside is finding a 4bt and the money they bring.Last 4bt i seen for sale around me was 2k and wasn't sure it ran.But i can get a running 12 valve 2500 to 3k or less if i look hard.

Re: 6BT rod knocker
 

That is some truth. Last one I found in CA for a decent price was over a year ago. And when they do pop up, they sell quick.

We put a 4BT in a 73 K5 and with the right gearing, NV4500, marine injectors and turbo it made some nice power. The way to get real power out of a 4BT is compounds. But nothing compared to what a mildly tuned 6BT can do.

But I would not waste my time putting a 4BT in a K30 crew cab.

Re: 6BT rod knocker
 

What's the advantage of the 4bt over the 6bt in our trucks other than less weight and slightly better fuel economy? The 6bt fits in fine, makes less noise, more power, costs less used and gets almost as good fuel economy if geared correctly.

Re: 6BT rod knocker
 

Time.

Took a weekend to drop the 4BT in the blazer. Mounts were simple, used an ORD BBC crossmember and no problems with fitment. Adding an intercooler to the NA motor was simple. Likes a higher RPM so no need to regear. Fired right up and sounds like a pissed off tractor.

Took 4 weeks and considerably more money to install the 6BT. Had to reinforce and over build everything in anticipation of the TQ. From mounts, crossmembers to hacking up the core support for the intercooler. And any missing parts are pricey to replace.

Just depends on your skill set and how far you want to go with it.

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Re: 6BT rod knocker
 

You can buy a swap crossmember with the motor mounts made in for both 4bt and 6bt http://www.cumminsdieselrepowers.com/Crossmembers.html

Re: 6BT rod knocker
 

those are crappy mounts, you break one and the motor is loose in there. I used the original chevy captured mounts, with upgraded inserts. 400plus hp, no problems. frame is not boxed either. i've had it in there for at least 10 years now. just made a new crossmember since the pan sits lower on those 6bts. tndiesel sells the mounts and crossmember like mine. no need to box the frame.
4bt doesn't get any better mileage in a heavy crewcab either. i've had 4 of them. same mileage out of my 6bt, and I can pull a gooseneck without overworking the motor. 4bt's are a novelty, but they're best for a smaller vehicle you're not going to tow much with. not that you can't, but you're maxing out the motor all the time and it won't make it to 400K like a 6bt will.

Re: 6BT rod knocker
 

These use the oem motor mounts https://www.gmcuminsconversions.com/...members-1.html