Been a while since I have been on here, but I thought of you guys today. Just got my 89 Dodge diesel back today, was busy getting a 4spd trans (47RH) with a lockup converter installed. Also running a whopping 27 degrees of timing from idle on up. Truck sounds like it's going to blow up pretty much all the time
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Anyhow, was crusing at 65mph or so with the window down, no aeromods, and a rocking chair and table in the bed (not so good for aero). It got 26mpg, backed up by 24mpg at 70-75mph next fillup. I think I could break 30mpg if I drove 55, the EGT gauge only reads 400 deg at that speed. The timing made an immense difference in low rpm power, and I could pull slight hills at only about 600 deg on the EGT gauge. The '89 Dodge diesels had 3.07 rear axle gears, so it has one heck of an overdrive, other than that, the timing is the only other real mod that would help fuel economy. Just figured I would share!