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Old 04-03-2007, 09:21 AM
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crazydog crazydog is offline
350 Buick
Join Date: Nov 19, 2005
Location: Permian Basin
Posts: 850
Originally Posted by tndonor
The front bumper is a BJs Offroad prototype they mocked up and sold here on the board I believe.

As for why the 4bt and what it is. The 4B is just like the 6B minus two cylinders.

One is the overall legnth of the 6B. It puts the rear valve cover and injection lines way back there and would probably involve partially taking the motor out for some basic service. Also running an air to air aftercooler and taurus electric fans so length was critical.

Two is fuel mileage. Most people are reporting about 25-30 miles per gallon versus 17ish for the 6b. My 4B has the coveted P7100 injection pump, not the rotary. Nothing wrong with the rotary.

From the factory, my 4b was spec'd at 350 ft lbs at 1300 rpm. I have a larger turbo, put the air to air and turned the fuel fuel up one revolution. I should be at 425-450 tq now. I also had a 3200 governor spring kit installed to get the rpms up if I am towing a load and need to keep i the power band.

And for gearing. The axles are 4.10, NV4500 5.6 to one first, Dana 300 2.6, Np 205 1.96 for a grand total of...........................119to 1

Finally a 4BT conversion where someone uses an aftercooler!!! Are you using a factory aftercooler from a Dodge or f*rd application, or something else or custom? Are you using the stock fuel plate? If you are you might try contacting TST and see if they have tried any plates on a 4BT.
1979 Cherokee - Built 401, NV4500, Dana 300, 6" BJ's Lift w/ Bilstein 5125 Shocks, Goodyear Wrangler MT/R 35X12.5R15, Front Brake Upgrade w/ GM 2500 Calipers & EBC Pads, Rear Disc Brake Conversion, Z&M Jeeps Dash Insert w/ VDO Series 1 Gauges, Tad Rack, Ramsey Hidden Winch w/ REP8000, Hydroboost, CS140

1967 J3500 - Making plans
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