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Old 07-13-2010, 11:19 AM   #1
mmichaud1
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Bronco Info: 1978 Bronco Ranger XLT. 351M .030 OVER, 600CFM EDELBROCK ON A WEIND INTAKE, 3G ALTENATOR UPGRAGE
i want better gas mileage out of my 78 Bronco please help me.

there has to be a way to get better gas milegage out of my 78 bronco short of dropping a 4 banger. the engine is pretty much stock except for the twelve year old rebuild that from what i was told was a mild one. i was just wondering if anyone was able to give me some info or help or point me in the right direction. by the way i love this sight it has given a lot of inspiration and info on how to work on my bronco right the first time. there are some very dedicated and professional people here. thanks for everything and i look forward to more and any i help i can give know or in the future. thanks mike m
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Old 07-13-2010, 11:25 AM   #2
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Bronco Info: 79 Ranger XLT-460,NP435,NP205,stock axles/3.50's,2.5"RC lift,33"trxxs mt's,72 impala horn(best mod)

nothing you do will yield goodgas mileage.....just keep her tuned up, and drive it easy.
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Old 07-13-2010, 11:26 AM   #3
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What are you getting now? Is the rest of it stock?
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Old 07-13-2010, 11:31 AM   #4
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Bronco Info: 79 bronco, 351M, 33x12.5 M/Ts, 2" lift
tire size? gears?
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Old 07-13-2010, 12:22 PM   #5
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It's a 6000lb barn door goin down the road. It won't be that good. I'm lucky to see 10mpg. Best I've ever seen is 13mpg goin down the highway.
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Old 07-13-2010, 12:59 PM   #6
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Bronco Info: 88 Centerion 460 Dana 60/10.25 78 Bronk Cromo shafts,Detoit 4.56's lift 7" Deavers 38's 9"rear disk
Ya It all depends on what you opinion of GOOD gas mileage is. Im very happy with the 12 mpg I get up here at 5500 ft 9mpg when Im towing the work trailer which is almost daily but it 6 to 7 thou lbs heavy. When I drive it down below 1000 ft elevation I get 15mpg+. Now this is with 35" tires and 4.56 gears after I put the lift on I lost 2 mpg on mileage.

Its all going to depend on how you drive it and how it is running.
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Old 07-13-2010, 01:27 PM   #7
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Bronco Info: 1986 Bronco XLT 4x4 -AOD -Warn Hubs, NEW stock 302EFI (2008) All MSD ignition, 9mm FMSR wires
Have you guys heard of this performance tip by FSB members Sweiv or Sixlitre where you can increase the plug gap and bump up the timing for better gas mileage and a bit more powerrange?

A lot depends on what engines you have in your Bronco's, ie: 302 or 351 preferably with Fuel Injected vehicles but in any case the theory should work with any engine, Carbed or FI, it's an old Hot Rodders trick.

Check it out!

Thread: ignition and timing upgrade...

Good Luck ~
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Old 07-13-2010, 01:33 PM   #8
mmichaud1
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Bronco Info: 1978 Bronco Ranger XLT. 351M .030 OVER, 600CFM EDELBROCK ON A WEIND INTAKE, 3G ALTENATOR UPGRAGE
after today it will be driving on 31x1050 r15's with a new front end rebuild.a new tune up on a 351m with stock 2 barrell carb which i will probably try and rebuild here soon. but i will try anything onece, twice if i like it. so im going to investigate and i will share my information with you. i will get to you all. there has got to be a better way.. there has got to be like an ancient star trek secret.
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Old 07-13-2010, 01:34 PM   #9
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Bronco Info: 1986 Bronco XLT 4x4 -AOD -Warn Hubs, NEW stock 302EFI (2008) All MSD ignition, 9mm FMSR wires
Bump
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Old 07-13-2010, 01:36 PM   #10
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Bronco Info: 1986 Bronco XLT 4x4 -AOD -Warn Hubs, NEW stock 302EFI (2008) All MSD ignition, 9mm FMSR wires
Bump! poor internet connections today!
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Old 07-13-2010, 03:00 PM   #11
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Bronco Info: 1986 Bronco XLT 4x4 -AOD -Warn Hubs, NEW stock 302EFI (2008) All MSD ignition, 9mm FMSR wires
Post #7 is your answer, check it out..


Good Luck ~
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Old 07-13-2010, 03:13 PM   #12
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Bronco Info: 1978 Bronco 6inch lift 37 MTR c6 auto 400 with holley carb
I hope to get better than my 7 to 8 mpg with mine? Your driving a bronco not a 2wd pickup what do you want more than 13 that's great mpg
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Old 07-13-2010, 03:29 PM   #13
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Bronco Info: 1986 Bronco XLT 4x4 -AOD -Warn Hubs, NEW stock 302EFI (2008) All MSD ignition, 9mm FMSR wires
To do justice to the "ignition and timing upgrade" performance tip, you do need all new ignition components including a 48K volt coil and in that way you get the maximum benefit....I use 9mm FMSR wires with MSD ignition components but there are less expensive components available as well....

Having the Carburetor in tip top shape is also another benefit along with good working throttle linkage so there's binding helps bring up the MPG's..

It's worth a try IMO, everybody here swears by this upgrade!

Good Luck ~
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Old 07-13-2010, 05:05 PM   #14
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After messing with my 400 for years and never getting better then 7-8mpg I built up a 460 and threw it in. My 460 has 3 times the Hp and 4 times the TQ and my mileage jumped to 10-12mpg. No one will ever convince me those 351m/400 motor are any good.

Both my 400 and 460 have similar mods I just truly believe the stock motors are garbage and do not respond well to mods. Now all the 351m/400 lovers will jump on me and show links to 500HP M/400 motors but I don't care. It's far easier to get power and milage out of a 460 IMO.
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Old 07-13-2010, 06:07 PM   #15
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Quote:
Originally Posted by 46079bronco View Post
My 460 has 3 times the Hp and 4 times the TQ and my mileage jumped to 10-12mpg. No one will ever convince me those 351m/400 motor are any good.
Right... show pics of your 1200 ft/lb 460.

1978 (400 ci) 149 hp @ 3200 rpm 300 ft/lb @ 1400 rpm
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Old 07-13-2010, 09:13 PM   #16
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Bronco Info: 1993 EB 5.8, eaod on 35"km2's 4" BDS lift. stock cats with glass pack muffler, axle code H9.
shouldnt buy a Bronco if you care about about mileage. most 4x4 will not yield DD MPG.
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Old 07-13-2010, 09:34 PM   #17
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Replace the retarded smog timing set with a straight up (0*) set.
A good valve grind helps.
Headers and a dual exhausr.
Check the fuel pressure and float level in the carb, replace the needle and seat.
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Old 07-13-2010, 09:41 PM   #18
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Bronco Info: 1994 Bronco 5.0 liter e4od factory MAF, 130 amp 3g, auxillary transmission filter and cooler.
do the sixlitre tune. remember the crucial parts are the wires, plugs, cap/rotor. stay away from msd. autolite/motorcraft coppers work best for plugs. the taylor spiropros are good but our engineer sig recommends the autolite professionals. a new stock coil will help a bit and just whatever brass cap and rotor you can get. personally im gonna try out a taylor cap and rotor since the price is awesome. its all outlined in the sixlitre discussion thread.

http://www.fullsizebronco.com/forum/...=63592&page=82

weve discussed these things in the last few pages.
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Old 07-13-2010, 11:22 PM   #19
Ianswild78
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Bronco Info: 1978 ford bronco. 351m np435 np205 3in of lift. 35" radial mud rovers.
wound a I-6 get good milage in a bronco?
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Old 07-14-2010, 03:31 AM   #20
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Bronco Info: 78XLT, 400-C6-205, D44 front and 8.8" rear at 4.10, 33" MTs on chromes w/ baby moons!
I'm going through the same process now, trying to trim gas mileage... and am getting stumped.

Gas mileage is a crap shoot in these trucks IMO.

I have a 400, 205, 4:10s and stock tires on my F250 and get 15 to 16mpg(highway)
I have a 400, 205, 4:10s and 33s on the bronc and get 6.5 to 7mpg(highway)

Same carb both, tuned the same, driven the same, on the same route/roads. The bronc should be slightly higher geared with the 33s calculated in, and its lighter....

Driving me nuts!

G.
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