Cummins 4BTA 2A One Ton HiCap

[oldhaven]

I've been driving this for about a year after a 10 year project. Noisy but surprisingly civilized. Full width F250 8 lug front, 14 bolt rear, Ford F350 ZF 5 spd with np 205, Defender/RR coil suspension, 68 mph highway cruise at 1800 rpm. Not sure if it belongs here but it looks like a LR, and I have two more real ones so I qualify. Ron Franklin, Bowdoin, Me.

[o2batsea]

There's room in there for a 6. Maybe the V10? Maybe have to move the rad to the cab roof for better fit! U GO BOY!

[landi41]

Not sure if it belongs here but it looks like a LR, and I have two more real ones so I qualify. Ron Franklin, Bowdoin, Me.

Oh i'd say you belong allright.........Nice job, no 1/2 measures there with that driveline either.........

[TeriAnn]

I've been driving this for about a year after a 10 year project. 68 mph highway cruise at 1800 rpm

The engine has lots of fans but you are one of the few that seem to have experience with one. A few questions:

1. How much does the engine weigh?

2. What is the engine max cruise RPM? what RPM range is the engine happiest with?

3. What R&P ratio do you have?

What is your low range first gear ratio?

Thanks!

[oldhaven]

Hi TeriAnn,
We spoke a bit about this project when I started it long ago, about the time your rig was in its second incarnation (or was it the third?) and it took this long since lots of (expensive) false starts happened along the way. I think I finally got it about right. It resembles the one-ton LR prototypes you can see in Lindsey Porter's book.

Thanks all for the compliments. I am pretty pleased and hope to make a few creature comfort improvements, like sound insulation, but is is well suited to its role as a work truck. I drive it nearly daily to work. I have used it in the woods quite a bit and it is quite literally a stump puller for me. I am not really into rock climbing or gettng lost in a mud pit on purpose. It is pretty light in the rear anyway with the aluminum bed (I can awkwardly pick the bed up by myself) so traction back there could be better. I will need to get a brake proportioner installed as the huge rear drums lock easily unless a light touch is used even though overall weight is pretty well balanced due to the engine position. (HydroBoost brakes with F150 power steering box run off an engine mounted gear driven hydraulic pump)

As for room for a Cummins 6. If a newer radiator panel from a Defender was used that would be quite possible, though this one seems to have all the power (torque) I need The 3.9 4BTA as used in boats can get 250 HP and huge torque. Mine is probably closer to 140, with 325 ft/lbs at 1876, which is 65 mph highway cruise in fifth OD. That is a happy point for the engine, and hills mean nothing. The non-automotive fuel pump works almost as a cruise control to maintain rpm with no pedal input, so I just watch the boost gauge and pyrometer. I hardly ever use first gear in high range as 3.04 second is a good starting gear.

The engine weighs 700 lbs more or less, while the cummins 6 is about 950, so that's another reason to avoid the bigger engine. It may vibrate a bit more, but I don't consider it unreasonable now.

Max comfortable rpm as my fuel pump is set is about 2600. It could turn 2800. I don't need that as I can do 70 with the 33 inch tires at 2020. 100mph is theoretically possible, but you won't see me there testing the theory. Axle ratios are 3.73. Final ratio in fifth high range with .76 OD is 2.83, final ratio in low range with the 5.72 first is 42.67 at which max torque is achieved at 4 mph and even at 2mph the torque is still above 200 ft/lbs. I have idle set at 750 rpm.

As for disadvantages, it does blow a bit of smoke when accelerating too quickly, (great for getting rid of tailgaters), and my dog can hear me coming a ways down the road due to the distinctive Cummins clatter and lets my wife know to expect me.

Ron

[yorker]

what is your average mpg?

[oldhaven]

I have yet to figure out the interface between the transfer case and the LR speedometer, so I drive by engine rpm for speeds. By watching the engine hour meter, guessing at average miles per hour run and how much and when I fill up the front and rear tanks I know I am getting over 20, but how much....???? If anybody knows of a way to plug two different speedo cable ratios into a black box and come out with correct speed and odometer I would appreciate knowing about it.

Ron

[leafsprung]

ditch the speedo cable and get a norscogg gps speedo

[oldhaven]

No mysteries, just a lot of welding and fitting

[Saxondog]

I've been driving this for about a year after a 10 year project. Noisy but surprisingly civilized. Full width F250 8 lug front, 14 bolt rear, Ford F350 ZF 5 spd with np 205, Defender/RR coil suspension, 68 mph highway cruise at 1800 rpm. Not sure if it belongs here but it looks like a LR, and I have two more real ones so I qualify. Ron Franklin, Bowdoin, Me.

Just got a 109 wagon, have been mulling over what to do to my new project. I have 2 generation 1 6BT dodges, a 1990 D350 dually 5 speed and a 1980 crew cab 4X4 currently undergoing off frame resto and conversion to the Cummins. I had been thinking about the 4BT for my next project the 109 Landrover. I see it's been some time since this thread was moving. Have you learned your MPG, I get 21 with the D350 dodge of mine. I figured the 4BT would do some better. Any other thoughs on your conversion. I want to do wider axles also, but though fullsize PU stuff would be too wide but yours looks good.