So a bit longer term update on this van. I tried advancing the timing 2 degrees, It lost 2mpg
It is a serious pain to work on so I haven't took the dashboard apart again so I can set it back to normal. I installed 2 transmission coolers, rear air bags, tach, MPGuino, and a torque converter lockup indicator light. I build a arduino based proportional trailer brake controller, I will post the schematics once I get it hooked up and working. I have a transgo HD2 shift kit and a corvette 2nd gear servo and billet 4th gear servo to install when the weather warms up.
Last week I took the belt driven fan off it and drove it to work and for the round trip the MPGuino was showing 3mpg better than normal. I had to put the fan back on it so I could haul some heavy stuff. I don't have all the parts I need to put electric fans on it yet but it looks like that should get me a couple of mpg at least.
Another interesting thing is having it in 3rd gear at 60mph gets only 0.3mpg less than 4th at 60. I am not really sure about why but I figure 95% of the engine load is aerodynamic drag so reducing rpms alone isn't going to show much of anything unless I can get the aero drag down some. Kind of eliminates the need to change from 3.73 gears to 3.08 if it is only going to show a 0.1mpg difference.
Apart from the minor engine stuff I can do like electric fans and underdrive pulleys I am mainly going to have to think up some aero stuff to do with it while still keeping it usable to haul and tow things. Anyone got any ideas for what mods to do to a box on wheels? I will try and put some better detail pics of the body shape when the weather clears up to help get some ideas on what can be done to improve it.