Less common in regards to conversion vans. I figured if I’m gonna get 10MPG no matter what, I might as well get the luxury of the headroom and TV to boot. Go big or go home.
That being said, this particular van seems to have an even larger hightop compared to other vans I’ve looked at and my buddy’s ‘97 Explorer conversion. This van is from Rainbow Vans Inc., which appear to have been a company local to Georgia. They’ve been defunct for years though, and I’ve been trying to get in contact with its CEO and CFO because I’ve wanted to gather as much information on this van as I can. So far nothing, though.
As long as I can remember mine got 17-19 mpg on long trips, sometimes close to 550 miles a tank. 97 low-top with a 350 Vortec, 4L60E and 3.42s. That rig would really benifit from a 4.10 or even 4.56 gear and locking differential of some kind. The 1-ton 10.5 had 3.73 gears and with the LT265/75R16 I was turning 3,000 rpm @ 70 in 3rd. Moved that differential up to a 5.13 gear and turn 2,850 in overdrive at 70 mph. With a stock 350 I would gear to turn around 2,800 rpm in 4th gear at your top cruising speed (usually 70 mph). I went a little more because I tow a 6,000 lbs travel trailer that is 11' tall, 8' wide and 26' overall length. My low top 97 got the same fuel mileage in 3rd as it did in 4th because of the frontal area so I regeared to turn slightly less rpm in 4th than it previously did in 3rd. My low-top van killed the stock 4L60e in 38K miles and the 4L65E built spec unit in 40K. Swapped to a 4L85E. I have also converted mine to a full 1-ton 8-lug suspension. With the conversion package the 1/2 ton model is sprung too lightly. I did an add a leaf first before towing my travel trailer and it did well with the stock van. I also went to Hellwig for a 1-3/8" rear sway bar and a 1-1/2" front sway bar. The front hellwig bar that size is listed for 03+ but the vans use the same front sway bar from 96-current. The 8.5 10-bolt is pretty weak in these vans but GM put a 9.5" 10-bolt under the 96-02 G2500 6-lug models that is a near direct bolt in-swap. Use the front rotors from the same van and you can run many of GMs nice aluminum 6-lug wheel options. Speaking of rotors, I swapped to a hydroboost from a 1-ton van with 1-ton front calipers even when I had the stock suspension and brakes. Way more stopping power for all the weight. A year ago I built a 383 to give me more power. Should have come from the factory with an aluminum head 383 is all I have to say.
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When you tune up one of these vans make sure you use good ignition parts. I have a good cap and rotor with brass terminals as well as Taylor Tundervolt 8.2mm wires with ceramic boots. The cheaper components even the AC Delco ones only last 2-3 years with the underhood heat. Even the factory manifolds cook the boots. I added LT1 metal heat shields onto the boots and that helped them live longer.
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