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Discussion Starter · #1 ·
I searched the board, but didn't find any mention of the Jacobs ignition and resulting better mileage...
I'm looking to get better mileage, and a bit more power from my Bronco. It's a 91 fullsize 302 AOD with 31" tires and only 57,000 miles on it.
I've got a K&N drop in, and a cat-back on it, which helped power a little bit... I'd still like to have enough power that it won't constantly have to shift out of OD in the hilly southern indiana/kentucky roads. I'd also like to get more than 12mpg on the highway.
Any cheap mods to help with this, until I save up for the bigger stuff?
I've been reading about computer chips, and the Jacobs mileage master ignition system. I've not found confirmation on whether these are compatible, and what kind of results I'll get from them individually and/or together. (besides the manufacturers claims)Anyone have one or both of these on their trucks?

I also plan on installing MAC shorty headers when funds allow.
Any help is appreciated!


Discussion Starter · #2 ·
I have always been skeptical that a new ignition system could really help your mileage much, so for 300 bucks for there systems it doesnt seem worthwile. Ive heard of a lot of people that spend 100 bucks on a high voltage coil, good plugs and good wires and let that be the end of it. A mod I have wanted to do for a while is an electric fan swap, another thing thats suppsoed to increase power because its one less thing for the engine to do. Shorty headers will work on speed density is what most people believe so those could be helpful. And as far as computer chips, most of them require you to run premium (91 octane) gasoline, which costs too much in my opinion, so the increased power and mileage is offset by the increased cost. The simple answer is there is no easy quick and cheap way to get power otherwise everyone wouldve done it by now.

Discussion Starter · #3 ·
My mileage improved quite a bit after installing the Jacobs off-road ignition, provided I keep my foot off the gas pedal. I get around 16-18 on the highway. Off road, in the mud, I believe I get WORSE than I did before, but a little more power...

· Registered
910 Posts
I have the MSD and Accel Ignition coil, It has given me 1or miles more per gallon, and a slight power boost. I added a Accel ignition box and have not noticed any diffrence, but nothing worked better for more power that to ditch the cats- especially the first one. This was probably the biggest increase I've had along with good performace muffler, and 2 1/2 pipes from engine to tip.
As far as shifting out of OD, it should shift out, most of us have the opposite problem, we wish it would downshift a little sooner to keep up the speed. Also if you have a 1991 it must have the E4OD, if there is a button on the dash to disenge OD then that's what you have. I'm pretty sure that that was the auto tranny used starting in 90. Put coil wires and plugs on as stated and chop the first cat and you notice an increase immediatly. good luck-Bob
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