Originally Posted by
Old81F100Brown
Brigette:235299
Thanks for putting our basic information on here, I write this stuff down under the hood and even then I don't get it all. Some of the stuff for these old, dependable trucks seems to just disappear! I write it in my manual, I write it on the forum, and when I need it, GONE. But I hit the over 60 timeline and I feel like I wake up, hide something, and then spend the rest of my day looking for it!!!
My search, that I have looked for over 3 months is this. I get about 12 Miles Per Gallon. Now I feel that with this light 302 as well as I have taken care of it, it should get a better MPG than I am. So I have posted, asked, begged, and called around. I have the Duraspark Ignition Module D8VE-12A199-A2C (With the Blue Grommet). I am sure that all that has been done with this truck is had the spark-plugs changed and Gaped, the oil changed, and the Air Filter Changed. On its regular basis. I don't know if I am supposed to time it, or even how to time it. I have gone around and changed out all the Vacuum hoses to no avail. I set the gap on the spark-plugs at .41
If I could change out the coil or do something like add the Duraspark II inferno coil kit would it let me open the gap up to .55 hotter spark, bugger gap, would that give me a smoother more economical ride?
No one seems to know if this can be done?!?!? With the price of petrol up past $4 It would seem to be something that us old trucksters would really want to know about. Has anyone done this. Could you tell me what you added to your Duraspark Ignition Module and how you did it to get better mileage? Please, help me keep my money either in my wallet or doing better upgrades to keep this ol girl running up to par. When I bought it I had the Engine rebuilt and the Tranny rebuilt in the early 80's.
I spent most of my time out at sea in Alaska so it shouldn't have to many miles on it. I didn't change the speedo so if I am going over 50 mph it pegs over 80. I think there is a GPS speedometer I can get to stop that problem. But my main concern is tune-up and efficiency. So I am doing the ol timing the mileage posts or following my wife at a certain speed to see why it can't pass a gas station!
Widening the gap will not help your mileage any noticeable difference, maybe just 1/2 mpg, that's just a guess. But nothing you would notice, and your plug and wire maintenance will increase.
The plug gap was set at the factory as a compromise between a good running engine, and plug life. You can widen the gap,, but it puts more strain on the whole system, the wires, the cap, rotor, etc. These have to be in top shape to tolerate the increase in gap, as the increase raises the voltage at which the spark jumps the gap. And the plugs have to be changed more often, as any wear increases the gap beyond what the system can handle. The factory gap gives you a good compromise between performance and life of the components.
I would not put a hot coil on the original Ford system. You don't get something for nothing, and this puts more load on the stock ignition module, which can cause it to heat up and shorten it's life. If you want more voltage capability of the system, you need a completely different system designed for it, along with the better wires, etc.
You do not say what truck you have, is it 4x4, what tranny you have, do you have a lift, what is your gearing in the differential, what size tires are you using etc? They all play a big part in your fuel mileage. Also, how is your engine setup? Is it completely stock with a 2bbl carb? Is it a California model with a computer controlled carb system?