1968 Jeep Truck Buildup - Project J2008, Part VIPosted in Project Vehicles on October 1, 2008 Comment (0)
The last time you saw our '68 pile of pickup we were outlining the drivetrain swap that we've started compiling parts and pieces for. Unfortunately, as often happens, delays put us a little behind schedule. We're still awaiting some induction components for the junkyard 4.0L XJ engine we obtained from Scotty's 4x4 in Fontana, California. The NP208 that M.I.T. in El Cajon rebuilt for us and the remanufactured NV3550 tranny and accoutrements we sourced from Advanced Adapters are raring to go. Hopefully we'll be able to pull the trigger on the drivetrain swap shortly after writing this and can bring you the photos and details.
Until then, we thought we'd bring you up to speed on a few of the little things that are required in any major vehicle buildup, but that are often overshadowed by bigger, flashier parts.
For starters, the original 275,000-mile 232 inline-six generated barely any oil pressure. We're talking like only 5-7 psi at 3,200 rpm and above. As a last-ditch effort, we drained out the 20W-50 motor oil and filled up the crankcase with straight 50W with two bottles of STP. The engine now builds 18-20 psi at 3,200 rpm. It'll probably run like that for another 200,000 miles if we cared to leave it alone.
Also, when we swapped in the Dodge Dana 44 front axle ("Project J2008, Part IV," July '08) we mentioned that the flat Dynatrac steering arm positioned the tie rod end right into the tire and allowed the drag link to contact the passenger-side leaf spring quite hard when turning left. It was so bad the truck really wasn't drivable. We called up Parts Mike for one of the company's new drop-forged, raised steering arms and it worked like a charm.
Another issue that arose from our Dodge front axle swap was that the disc brakes of the new axle dragged when used with the original master cylinder. Drum brakes require more initial line pressure than disc brakes to properly energize. Without a residual pressure valve holding some line pressure to the drum brake wheel cylinders in order to covercome the force of the brake shoe return springs, you would need to pump the brake pedal at least a couple times before the brakes grabbed. Since the disc brakes don't require this residual pressure to energize, they'll drag unless the pressure is released. We employed an old-school trick to save some coin on a new master cylinder.
Finally, the antique three-wire Motorcraft voltage regulator quit working, allowing alternator output to vary wildly from more than 15V to less than 10V. A replacement at our local Car Quest was over $70, so rather than take it in the shorts on a part we'll likely be yanking when the engine swap happens, we simply modified our stock alternator bracket so we could fit the GM large-case 100-amp one-wire alternator off our '68 M-715.
Now that we've got our J2000 drivable again, we've been using it to cruise to the office at a mind-numbing 53 mph and for hauling garbage to the dump. Hopefully next time you see our FSJ it will be sporting an upgraded engine and overdrive tranny to deal with the 33-inch tires and 4.56 axle gears.