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1st gen Dakotas with V8s weight about 1000lbs more than a 318 2bbl a-body. The 3.9 V6 is for MPG than the 318 but not much in a dakota, my 2000 4x4 ex cab gets 18-21 on the highway and tows just fine as long as you don't expect it to pull a car over a pass @ 75 mph. A 3.9 magnum would move an a-body handily, a 4cyl a-body will get better MPG than a 4cyl dakota because it is still around 1000 lbs lighter. Do not be afraid to try it, I would run a 3.23 gear and an a-500 and I would bet you could get 30 mpg and handily kill an average slant six in a drag race.

Now if you want to really go all out on it, get a 5 speed to swap in and install a set of 6 KB167 pistons and get the cam reground with slightly more lift or install some 1.7 roller rockers for nearly the same effect. Put a V8 throttle body on it and fill in some of the plenum area in the beer barrel intake. You will probably need some custom headers for the best MPG.



great minds think alike. if I were to use a 3.9, I'd use KB167's at 0 deck, and have the cam reground by bullit with the same lobes I'm using in my 318 (HR259/316) and toss a V8 TB on it.

one downer, IIRC, the 3.9 only has the newer truck mounts, not the old LA ears on it, so you'd still have to get creative on fabbing motor mounts.

I'd probably look at a 3.5L out of an LX. heck, even a 3.8L out of a wrangler in a light A body would be decent--our 4400 lb caravan gets pulled around by one just fine, would be downright peppy in a 1300 lb lighter car....toss it in front of an A833OD or AX15 and 3.21's



Well, if you're already talking about building an engine then you have some money to blow. That gives you more options.

The 3.9 just doesn't sound like an efficient engine. 3800lb truck, 2800lb car, an inefficient 3.9 is an inefficient 3.9. Why not look for a different plant? The 4.7L DOHC V8 will probably get similar mpg, make way more power and sound better than a 318 ever could. Dont even unbolt the OD tranny from the back if you can get away with it.

A N/A 4cyl engine in a 2800-3000lb car would probably suck. Thing is, stuff a 4cyl engine into an A-body and you'd have to seriously do something wrong to have it weigh that much. If a slant 6 weighs 425-475lbs (??? they are NOT light...) and likely comes with a heavy trans too, then what could a modern all alum 4cyl weigh with a modern 5spd? People have had 67-up A-bodies done out with 225's and weigh 2600lbs easy. 4cyl? how about 2500lbs? 2400lbs...??? NOW you might have something... You can now get away with flimsy cooling, driveshaft, diff, all kinda ov stuff. 2400 could get liberal...

Read up on the 4cyl Fox body Mustang guys... Some ov those guys are doing basic, non-invasive mods on their cars... again, already light cars before they start weight-reduction, and are keeping up with stock 5.0L Foxes with these 2.3/T5 cars. My brother had a 2700-2800lb 69 Valiant Signet with a bunch ov heavy stuff in it, and a hot-rodded 225/A833OD/8 1/4" set up. That car could have been 2600lbs easy. Convert to 4cyl and it could have been 2400. And THEN you could get into fiberglass and really serious weight-loss measures... Now, start with an earlier, lighter body style...

Hmmm...

One thing though... i will never understand the draw ov turbo'd 4cyl engines. Sure... you can make V8 power. So... why not use a V8...??? Far less BS to deal with at that power level, the same bloody gas-mileage, and it doesn't sound like smashed ass. Cars with no engine bay? sure. The pinto guys have a point. But if you've got room...