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post #1 of (permalink) Old 11-13-2001, 06:48 PM Thread Starter
 
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Fuel mileage? again

I'm lookin at a 86 Bronco with a fuel injected 302 Auto w/overdrive and 3.08 gears.What sort of fuel mileage am I looking at?Thanks.

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post #2 of (permalink) Old 11-13-2001, 07:08 PM
 
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Re: Fuel mileage? again

My 86 302 EFI'd Eddie with an AOD and 3.55s routinely gets 15-16 all round

It's hard pressed to get less than 12mpg (American gallons) even when I'm roddin' the bejeepers out of it. I've actually pulled 19.75 all round in the Summer and even better on the hwy. If you step too much over 2000rpms in OD it nose dives pretty fast though.

Mine has 15,000 miles on it since the new longblock and the rest of the drivetrain has 160,000 miles + on it. Make sure your ignition system is optimum. I'm running an MSD-6, MSD TFI style coil, extra thick premium dist cap, 8mm wires and the plugs set to .060.

No other single thing improved my mileage as much as all those ignition upgrades. Really put the snort back in the 302 too. The K&N filter is on there too and must help and I axed my second cat as she was split right down the side. The blockage there was a big fuel waster.

With 3.08s you'd better be running a pretty short tire or doing all roadwork with it as you won't get much grunt out of it in the bush. A tall tire will kill your acceleration.

Malcolm

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post #3 of (permalink) Old 11-13-2001, 07:29 PM
 
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Re: Fuel mileage? again

That summer mileage still gets me Sixlitre, I remember you posting that a couple weeks back. With the 351, 4.10, and 35's I guess I do 11-12 city, 14-15 highway, which isn't bad, but there is always room for improvement! I have a K&N filter, Brass cap/rotor, jacobs wires, accel coil. I'm interested in two things: Did you put on all the ignition components at once? I'm wondering if you did this over time and maybe had insight on the different components. I'm still debating the MSD-6A, or stick with just what I have. Also, I have run the gap out a little with my current ignition, to .051, but did not seem to help at all. Any particular plug you like? I've been kinda partial to the Autolite Platinum Pros. They don't necessarily give extra performance except in longevity.

The Juice, '95 Ford Bronco XLT, White, 5.8, E4OD, 4" Rancho, 35's, 4.10, ARB/LSD, lots else
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post #4 of (permalink) Old 11-13-2001, 07:57 PM
 
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Re: Fuel mileage? again

Juice

Those Jacobs components are the cat's ass, but pretty pricey. The best cap I ever bought form my Mopar was from him. Had to be triple thickness. It's easily 8 years old and still going strong.

You're right about doing it bit by bit, that's how I did it. The MSD-6 I did last and wasn't that noticeable mileage wise, but it was quite noticably better in acceleration. The MSD TFI style coil and gap opening up did the most. I think it was Muddy who told me the Chevy boys don't even bother with the MSD control unioot, just the coil. He was right, it worked for me.

Then someone here mentioned the Crane control unit and coil was less money and better than the MSD.....Doah !!!!!! too late the MSD is paid for.

Your mileage is great for a bigger motor, steeper gears and heavier tires than I run. I'm running street Dunlop GT 275/60/15s so I don't tip over like a Bronco II or Blazer on ramps.

I run AC Delcos and was at .051 before the MSD-6.

Malcolm

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post #5 of (permalink) Old 11-14-2001, 07:45 AM
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Re: Fuel mileage? again

Malcolm, its probably your low mileage rebuild that helps the most, thats what dramatically improved mine(i have 6K on it now). Or MAYBE its that frigid dense CANADIAN air[img]/wwwthreads_images/icons/laugh.gif[/img]dont need to turn the a/c compressor. I wonder if you would still get that good of mileage down here in floridas sweltering heat.[img]/wwwthreads_images/icons/crazy.gif[/img]

My ignition box and K&N filter did very little if any at all to help on mileage, the Flowmaster Cat-back may have helped a little as it made a noticable difference in power.

I was told by performance shops and engine builders NOT to open the gap more(the crane ign manual also states) cause the plugs wear a lot faster with high energy ignition boxes. i had tried 050" though and didnt see any improvement. Im running AC delco rapid-fire plugs in it now.


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post #6 of (permalink) Old 11-14-2001, 07:45 AM
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Re: Fuel mileage? again

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post #7 of (permalink) Old 11-14-2001, 07:20 PM
 
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Re: Fuel mileage? again

You might have something with the mileage of the engine as well. I actually did better when it was newer. Unfortunately, with all the mods I can't directly compare old vs. new. AtI one point in the Bronco's life (25k to about 45K) I had no mods, 31" tires, 3.55's and swear that on my trip from back east to our last home in Denver, The Juice got between 16 and 17, almost all highway, straight (slow uphill), with some cargo. Best mileage I ever got.

The Juice, '95 Ford Bronco XLT, White, 5.8, E4OD, 4" Rancho, 35's, 4.10, ARB/LSD, lots else
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post #8 of (permalink) Old 11-14-2001, 07:33 PM
 
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Re: Fuel mileage? again

Yeah you guys do have a point with the fact the longblock is still fairly new

Still it did do pretty well the first two months after I bought it with the 160,000 mile original motor, before I took it up to Baffin Island for those 2 years. I don't remember how much the A/C scrubbed off the mileage then and it ain't recharged now to try it. Strangely Canada's Southern Summers seem to give me my best mileage.

After reading Dr.Jacobs book and all the MSD literature and Mopar Performance bulletins I'm pretty much sold on bigger than stock spark plug gaps. This is also born out by the fact Ford went to a larger gap in their stock EFI motors in 85 or 86. Before it was .035 wasn't it ? Then they went to .044-.046 recommended gap.

I know it made a major power gain on my Mopar and the mileage was up too. Granted the 302 was better at .051 and no different in mileage at .060. Both moves up with the Ford did gain noticeable acceleration (snort) improvements according to the seat of my pants meter and the intake howl.

Wish I'd known about that cheaper, supposedly better Crane system before I popped for the MSD set up.

Malcolm

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post #9 of (permalink) Old 11-16-2001, 11:36 AM
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Re: Fuel mileage? again

My system is stock on my 93 302. What parts and what order should I start replacing the old to see improvement. Please be a specific as possible.

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post #10 of (permalink) Old 11-17-2001, 12:08 AM
 
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Re: Fuel mileage? again

Well I'm gonna assume you're after mileage more than power, okay ?

If all your ignition stuff is now 9 model years old I would do the following things first. Buy a Jacobs dist cap and rotor or one that is super thick with brass terminals. Next pop for 8mm spark plug wires to carry the upgraded spark you're going to generate.

Then decide either Crane contoller and coil or MSD controller and coil. I used the MSD #8227 TFI stock style Ford coil. This bolts on and can be used with the standard ignition until you decide whether or not to use the controller unit. Like I said, the coil, with the gap opened up to .051, gave the biggest mileage improvement.

The MSD-6 I added later didn't add any noticeable mileage improvements but it did idle and accelerate better for it. They also sell a neat adapter wire with stock Ford style plugs that lets you disconnect/bypass the MSD-6 anytime you're trouble shooting and run the regular ignition to fire the coil.

The K&N air filter and filter charger would be another move you could make. After that I'd free up your exhaust with a large, efficient cat back single system. Synthetic everything would also help. I run synthetic axle fluid, tranny fluid and did run it in the crankcase for a while.

Grease the wheel bearing again with synthetic grease and run the least aggressive tread pattern, if 99% of your travel is on the hwy, like me. An under inflated tire can easily cost a mpg or two as well.

Start there and read back through the posts searching "mileage". I'll add more as I think of it.

Malcolm

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