Engine swap? Options?

[Orangecrush]

As previously mentioned, my 351w powered bronco's getting about 6 mpg city (if carefully driven) and maybe 8 or so on the highway. let's face it, for an "often driven" vehicle, that's just INSANE. I don't care how nice the truck is. So, rather than selling the thing, I'm considering my options. What if I swapped out the 351W and C4 for something modern?

Does anyone have any experience here? I may have trouble swapping the A/C over to a moder engine without significant mods; but other than that, what motor will work with a vintage bronco? 4.6 mod motor? What about the tranny?

Ideas??

 

[jagscars]

You should be doing alot better than that. What carb.,cam,etc. are you running?You could do a f.i. setup for alot less trouble. Without any knoledge of your motor,drivetrain setup I'd first look at your long and hard.

Oh...duh I just saw the bottom of your post...

 

[Broncoholics]

Might try a smaller carb. I found Carter to get great gas milage. I only ran a 600cfm on a 351 and it ran perfect out of the box. Edelbrock is OK but sucks off camber. Q-Jet really sucks the gas due to large secondaries so stay away from them. I find Holley pukes over time. Demon I've heard 50/50 likes and disliks, never ran one myself.

My 302 with 289 heads gets good milage.

 

[Orangecrush]

Might try a smaller carb. I found Carter to get great gas milage. I only ran a 600cfm on a 351 and it ran perfect out of the box.  Edelbrock is OK but sucks off camber. Q-Jet really sucks the gas due to large secondaries so stay away from them. I find Holley pukes over time. Demon I've heard 50/50 likes and disliks, never ran one myself.My 302 with 289 heads gets good milage.

30480[/snapback]

​

Yea, I'm now running a 650 demon; but, I've got a heavy spring in; so, the back 2 ports should not open until like 3000rpm.

Oh also, I realized that the throttle wasn't closing all the way (sticking open slightly) at idle.......so I'd have to always "blip" the throttle to bring it back down. I wonder how much extra fuel I was burning just because of this around town? Last night, I put in a really strong spring which shuts the throttle blades completely every time I let off the gas. I just put 10 gallons in the tank. We'll see if this helps much. I used to be filling back up at 58-64 miloes on the 10 gallons. I'll keep you posted. If it doesn't get up to 80-100 miles, I've got to do something.

 

[Broncoholics]

Sounds to me that the choke is sticking. You can change you electric to manual so you know its out of the loope.

 

[76Explorer]

the gear ratio of your axle verses tire size will affect mpg, check out this link.

http://www.4wheelparts.com/4wp/help/help_p...ratio_chart.htm

 

[jfarish]

I have a 351w with a 650TA and it gets atleast 10 mpg if you want to go newer I would try fuel injection.