Man I am stoked. After 3 years of collecting parts, probably $2000 and a month and a half of work I can finally say my truck went from an abysmal 7.3 MPG to an equally abysmal 7.45 MPG!

That's YUUUUGE!

I have to admit surprise. The lockup torque converter was supposed to be good for 3%. The A727 was supposed to suck up ~ 45 hp. You used the NV4500?

Yeah an NV4500 to replace the about ready to grenade NP435. In all honesty I didn't do the swap for fuel mileage, it was my original intention when I started gathering parts for it because I drove a lot of highway miles in FL. Here, maybe 70 highway miles a month, so I knew it wasn't going to be a drastic change. The truck spends most of it's time around here under 30 MPH. The upside is I can actually drive it at 70 now, my ears don't ring for two weeks after I drive it and I now have A/C. So that figure is with A/C on that the truck never had before.

Maybe the bright side is that with fuel prices nowadays, that's saving you $20--$30 per month
So, multiply & divide and throw a dart, and...never mind...

It's a solid fuel saver now, why own a hybrid?

I did a Tremec 5 speed manual swap in my Charger. I got 15.1 mpg driving @ 70 mph. MY previous best was 12.8 @ 65.
I am sure that I can get to the mid 16s if I dialed it back a bit.

Does that Magnum V8 now have a barb instead of the fuel injection?

It's still an LA with Magnum heads and front drive assembly so yeah, it has a Holley style 650 vacuum secondary carb.

What gears are in it?

4.10s with a 31" tall tire. It has on paper a 8.9:1 compression ratio and a small 220/220 @ .050 cam with .478 lift and a 108 LSA. Heads are bone stock Magnums and the engine is .040 over. Edelbrock Performer RPM air gap intake and a 1" carb spacer. It has light spark knock under moderate load on 87 pump swill. I've knocked the timing back to 28° total at 2700. I don't want to go any farther.

Sounds like my dad's '72 Travelall 4x4 with the 345. it got 7 mpg. City driving; 65 mph highway driving; pulling a '69 Chrysler 300 demolition derby car on a tandem-dual trailer for 200 miles at WOT: 7 mpg...

It's weird how that works: way back I had an '85 Chevy C20, carbureted 454/400, got about 7 MPG no matter what speed or load.
The '89 GMC Dually I've had for a long time, FI 454/400/GV, gets 10-11 MPG whether it's loaded up & towing, or empty. (Pre-GV, it got 7-8 MPG.)
Before oxygenated & ethanol gas, I once threw everything I could think of at it, and on a steady freeway Cruise, just made 12 empty.
Good thing is it doesn't care about octane, thank God.

Jones, I'd be curious what your rig would get with more timing and octane.

I might experiment with it a little later on. Right now I'm just concentrating on the small finishing details.
The truck lost the WWII Jeep vibe it had going on. It's like driving a new truck now, quiet, nice audio system, power windows at all 4 corners, intermittent wipers, A/C of course and more.

with that gearing and aerodynamics that MPG is not out of line,
especially if parts of trips are off road and on hilly country roads


sometime in the future use an oxygen sensor to find out your “ballpark” air to fuel ratio at level highway cruise

That timing curve is waaaay too conservative for that motor. It should not be anywhere near spark knock, maybe you have a fuel line too close to exhaust somewhere or insufficient air flow under hood or something. That engine should easily take 32-35 degrees mechanical timing and that would help MPG quite a bit. I would try bumping the timing to 35 and run premium through it a couple tanks to see if it is worthwhile to run premium by getting much better MPG. I had a nearly identical cam in a magnum 410 iron magnum headed stroker motor with 11 to1 compression and it would run 32 degrees timing on premium with no knocking.

I had it at 33° before the swap but the howling coming out of the trans was so loud I never heard any spark knock. It is really light. I'll experiment with it after I get the little things taken care of. I'm waiting on a couple 10" 1000 cfm fans I'm going to put on the condenser and a trailer brake controller. I think I got the fuel gauge working decently now. I may even put a slightly colder plug in it.