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Discussion Starter #1
I have a 79 bronco with a 460/C6, other than the fact that it's carb'd it runs great. Sometimes I even get 11 mpg! The downsides are it stalls a lot off road and there is some serious weight in the front end. How would a 351W/NP435 work out? My guess is I would lose 150lbs or so and pick up a couple mpg's, plus fitting an aftermarket EFI system would be easier... True? Not True? Total waste of $$$?
 

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I honestly don't know that you're gonna see much of a mileage improvement with a 351W..............my '90 with E4OD gets 11 give or take....

As for "aftermarket" EFI we'd need to know what system you have in mind. You can fit TBI to that 460 without much trouble, hardest part will be finding a 454 throttle body.
 

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Discussion Starter #3
I figured the transmission swap would lead to a small mileage improvement, the C6 being famously inefficient and all...
 

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kdsheldon said:
I figured the transmission swap would lead to a small mileage improvement, the C6 being famously inefficient and all...
So you are willing to go through the whole process of swapping out to a Windsor (351W efi at that), motor mounts, drivetrain cross-member, and transmission etc. just to gain MAYBE 2 miles per gallon and help with the stalling???

For the stalling off-camber, I would install a Quadrajet. If you already have one, a rebuild may be necessary.

You stated you sometimes get "11 mpg!!" in your 460/C6 '79 Bronco, that is a great mpg for your vehicle's weight and engine/trans. combo. I doubt you would see better numbers in your Bronco with a 351W/NP435 combo.

Why a NP435?? Do you already have one?? Think it'll be easy to swap in?? Why not a ZF 5-speed?

Numerous pros/cons exist for MANUALS as well as AUTOS. I wouldn't say C6's are famously inefficient. All autos are somewhat less efficient when directly compared with manuals regarding the transfer of engine power to the drivetrain. Yet, they have advantages over manuals too.
 

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The 460/C6/205 combo in a fs Bronco is solid. I'd run propane and wheel the biatch! No more stalling and you might even pick up a mile or 2 in mpg in the process;)
 

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if you do not want to put it on propane why not just find a 460 efi and swap it all over.
 

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My 429 gets 10 mpg pretty much all the time, loaded or not.

My 351W gets 12-13 on the highway with a 670 Holley TA but drops to 10-ish when I'm screwing around.

I can't believe you're considering the expense and PITA factor of an engine/tranny swap for a 10-20% increase in mileage. Have you done the math to figure out how many miles you are going to have to drive to pay it off?

If you're thinking small block, why not 5.0?
 

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stick a Q-jet on there. i run one on mine and get up to 13 mpg if i stay on the little primarys. plus it will help alot with the stalling problems.
 

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the 351W injected in the work van I have outside (light vans.. we could get away with e150's but have e250's for some reason) gets 10mpg on a good say. keep the 460.
 

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My theory on gas milage:
It takes X amount of BTU's (or horsepower or however you want to measure the energy) to move a given amount of weight. A gallon of fuel is only capable of generating so much energy, and the ideal ratio of fuel/air is fixed.
The short version: reduce the weight if you want better mileage.
That would give the appearance that a smaller engine is more efficient, but in my opinion any gain in mpg would be due to the weight reduction.
I have NO FACTS to back this up... that's the cool thing about the internet.
 

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78bronco460 said:
I have NO FACTS to back this up... that's the cool thing about the internet.

you sir.

Have made my signature
 

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heh, one thing you guys forget to mention here, goin from a big block to a small block sucks ass. The day you mash the go pedal and the motor doesnt stand up and say sir yes sir, thank you sir may I have another. You will hear something more like this [droopy_voice] Oh boy, do I have to do this again. This is so hard[/droopy_voice]

Its not about miles per gallon, its about SMILES per gallon!!!!
 

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Discussion Starter #15
Hey all, that's why I threw the idea out for discussion in the first place. So how hard is it to convert a gasser to propane?
 

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I have a 79 Bronco, 400/NP435 4.10 gears on 38in TSLs and when I smack the go pedal it definately has some go to it. It aint no 500HP monster but for a full size I dont think its bad. Its a pure trail rig so I dunno my gas mileage.
 
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