We swear, our ongoing 4.0L, NV3550, and NP208 conversion into our '68 J2000 pickup is so close to completion we can taste it. As you'll see in this issue, the wiring and fuel system is sorted and we're just waiting on a couple odds and ends to arrive before we'll be driving our (hopefully) powerful and efficient J-truck down the road.
We still need to have driveshafts built, toss the radiator back in, modify the exhaust from the 232 engine to fit our new, longer drivetrain, and throw a steering box into the equation so our power steering pump doesn't run dry and explode. We'll bring you all those details next time. Until then, check our progress so far.
Like any 40-year old vehicle,...
Like any 40-year old vehicle, the wiring harness in our '68 J2000 was a nightmare of half-assed previous owner modifications and mystery wires that no longer connected to anything. It was just easier to rip out everything with the exception of the light harness and start from scratch
Since it's a So Cal truck...
Since it's a So Cal truck and this author prefers simple over complicated, the heater assembly got the heave-ho. If needed in the future, a Flex-A-Lite Mojave heater will be installed. The resulting space left plenty of room for mounting the factory 4.0L computer inside under the dash.
The Hotwire Auto-modified...
The Hotwire Auto-modified factory harness we showed you in Part VII of this series took literally five minutes to install. All the connectors were labeled and the protective loom was already installed. It was just a matter of routing the harness and plugging in connectors.
Inside, Hotwire Auto couldn't...
Inside, Hotwire Auto couldn't have made things easier for us. To power the factory computer we hooked up wires for the chassis ground, constant 12-volt power, and key-on 12-volt power and called it done.
Since our junkyard engine...
Since our junkyard engine didn't come with a crank position sensor, we hit our local auto parts store for a stock replacement. There were several different terminal types used through the years, so make sure you note your connector pin arrangement before buying.
The earlier H.O. engines used...
The earlier H.O. engines used a firewall-mounted MAP sensor. We had the one from the junkyard '92 XJ, so we screwed it to the firewall and plugged in the connector. The sensor must also be connected to a source of manifold vacuum. We used the stock vacuum line that was still attached to the MAP sensor.
We asked Hotwire Auto to leave...
We asked Hotwire Auto to leave enough length in the harness to mount our fuse block, computer, and relays inside on the passenger-side firewall. We ran the 60-pin connector through the hole in the firewall left by the deleted heater assembly. We'll build a two-piece cover plate so we'll be able to remove the connector again in the future if needed.
Hotwire Auto installed this...
Hotwire Auto installed this fuse block to control the various wiring left in our harness at our request. When we get around to it we'll be able to have cruise control, backup lights, air conditioning, electric fan(s) and a variety of other amenities controlled by the factory computer.
One thing we noticed when...
One thing we noticed when we had the transmission shifter off our NV3550 was that the unit didn't have any fluid in it. Normally Advance Adapters ships all of its NV3550s full of fluid to prevent the installer from filling with the wrong fluid, but we dropped in to pick up our unit before the company filled it. The fill and drain plugs are a 17mm hex socket, but the head of a metric bolt works equally well.
To prevent damage and ensure...
To prevent damage and ensure proper operation, you must fill the NV3550 with 2.4 quarts of Mopar PN 04874464 fluid. Pennzoil Synchromesh or Royal Purple Synchromax fluid is also acceptable. We removed the shifter assembly and just poured the fluid straight in rather than messing with funnels and oil pumps.
We had thought that we could...
We had thought that we could make our factory throttle cable work, but it had been butchered some time in the past and didn't have enough cable to swedge a factory clip-on connector to. We ordered a replacement XJ cable from our dealership for a quick fix.
Our '92 H.O. 4.0L requires...
Our '92 H.O. 4.0L requires a fuel pump that can deliver at least 39psi to prevent fuel starvation. The factory fuel pressure regulator will keep the pressure to the injectors at around 31psi. To make our life simple, we called Hesco for its Rear Mount Fuel Pump/Filter kit, PN HESRFK1, which comes complete with hose, clamps, filter, and a high-output fuel pump
The fuel pump should be mounted...
The fuel pump should be mounted close to the fuel tank. Hotwire Auto included a provision for an electric fuel pump in our harness, so hooking it up was as easy as running the wire to the pump and hooking up the power feed and ground wires. The fuel filter should be mounted before the pump to keep debris out of the pump vanes.
One thing you'll need to...
One thing you'll need to address about the older HO engines with an external fuel pressure regulator is the fuel return line to the tank. Rather than drop the tank we ran a line to the fuel filler hose. We thought about welding a bung to the metal portion of the filler hose, but instead used a bulkhead connector through the rubber part for a safer install.
We called up Turbo City for...
We called up Turbo City for one of its high-flow cold air intakes for our 4.0L. The intake uses an open-ended K&N oil impregnated gauze filter for maximum flow, which given our engine's Edelbrock header and lack of a catalytic converter we may appreciate. Turbo City routes the filter to the passenger-side of the engine so it's not sucking hot air off the exhaust manifold.
Even though our engine is...
Even though our engine is hooked up and ready, we still can't fire it up since our truck runs a manual steering box. We had planned on simply removing the power steering pump and A/C compressor from the engine, but since the serpentine belt adjustment is accomplished via the power steering pulley it was just easier to leave it all there. We'll wait until we nab a steering box that will work to fire it up, although Cappa suggests that we can simply hook the pressure line up to the pump's return port without issue. We may try that route if our hunt for a suitable junkyard box turns up nothing.