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Discussion Starter #1
i was wondering what mod's that i do to my engine would effect the gas mileage? cause i cannot really afford to get any lower gas mileage than i'm getting. but i would like to do some stuff to my engine to give me more power. but i'm not sure what area's would effect the mileage or anything else. wish i knew a little bit more about cars. so yea any info would be helpful :) thanks
 

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A good tuneup (for economy) is the easiest starting point. Most of us Cougar owners tune for power, not economy. Basic things like upgrading your ignition system and changing your fuel filter can help. Keep your air filter clean, maybe get a K&N high flow filter. I've even heard that switching from the stock 2v carb to a 4v carb CAN get you better gas mileage, provided the tuning is correct and you can keep your foot off the firewall (I can't).
First and foremost, though, I would upgrade your ignition (plugs, wires, maybe an electronic distributor, even an MSD box, which I don't know much about), change your fuel and air filters, and do a good tune up. The aftermarket distributor I bought (Accel electronic breakerless) had a nice little chart showing how the timing should be set for power, and how it should be set for fuel economy, including a nice graph of where the "mid-point" between these two is.
 

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Discussion Starter #3
cool thx, yea i just tuned the thing about 3 weeks ago and it really didn't need it that bad. i just bought a K&N air filter yesterday, so i'm fine there :) i'll have to get a fuel filter next. the only prob with ignition box is that its kinda expensive if i remember right. so that will be a while. what about like changing the cam? would that affect it at all?
 

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Changing the cam will have an effect on fuel economy -- usually for the worse. Aftermarket cams are typically built for increased power, meaning more valve lift, duration, and overlap. Lift and duration could actually aid fuel economy, in certain applications, but overlap usually hurts. Generally, performance cams also move the powerband up the rpm curve; unfortunately, to maximize fuel economy you'll need to keep engine rpms as low as possible. (If you drive a manual trans, you'll get the maximum fuel economy when you shift at the lowest rpm without causing your engine to bog in your new gear)
Ignition boxes are expensive (in the range of $100-200 I think), but from what I've heard they're worth it. I've personally never used one, though.
 

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When you say you tuned the car, did you optimize the timing curve? There is usually more AND better mpg's to be found in a good tune. There are two ways to check the timing curve, that is with either a standard timing light and a degreed balancer or a dial back timing light---Sears has a nice one for $69.95, they call it an Advance Timing Light. It is my most used tuning tool.
Setting the proper timing curve is very important to a well running street engine. The street engine has to perform in all ranges and as the engine revs under different loads the ignition timing needs to vary to stay optomisd in the particular range. In comparison, race engines operate in a narrow range and can get by with the timing locked in one position, or a narrow curve.
I don't believe that there are different timing setting for power and ecomomy, but that there is just one best setting. Figure that you have an engine running in a fixed situation like on a dyno or a water pump, also you have a fixed amount of air/fuel given to the engine. There are 3 possible examples for this situation: Say for #1---- with the timing set at 36 degrees you made the most power---on that fixed amount of fuel. #2 ---If you advance the timing more, the power will go down from lighting the mixture too early, either giving a push-back sensation on the piston or detonation will occur which is good for a fire cracker but does not provide the correct progressive push as needed in an engine. #3---you retard the timing for possible better economy, but this doesn't work because lighting the mixture off too late will not allow the working pressure to reach peak and/or still be in the process of burning the air/fuel mix when the exhaust valve opens. With an open valve the pressure in the chamber is no longer harnessed and the remainder of burning takes place in the exhaust pipes----thus wasting fuel. All in all, there is only one best.
The basic comes down to "it takes fuel to make power". It is the fuel that contains the energy so if you want the fire hotter you need to add more fuel. But that doesn't mean to install bigger jets in the carb, here again, there is only one best carb setting or timing setting for a particular engine combination. If someone advances their timing to make more power, all that means is their previous timing wasn't correct for that combination in that particular range. With the timing advanced the top end power was better, but it seemed too advanced for crusing around town. This tells you that the timing curve range is too narrow and other possibilities like too much range in the vacuum advance.
But, before you spend a lot of time optomising your timing, you need to determine what engine componants you desire to use. For instance if you change from a stock cam to a longer duration camshaft, your optimal timing requirements will change too.
Here is a street combo I'd recomend, a 4v carb and intake whether it is stock or like an Edelbrock performer, a fast ramp cam with 210-220 @.050 duration on the intake and set up the exhaust with a split pattern if nessesary. Headers will help the power, without taking away from drivability. Go for a smaller sized tube header if you can. Run dual exhaust with a crossover, I preffer the X style myself, through performance mufflers and make sure to run tail pipes to have a completed job. That is just a basic, when it comes to assmebling an engine like that, there are many other things to take into consideration like port flow, quench and all the clearances just to name a few.
As far as the MSD goes, the measurable gain on a well tuned street motor is marginal. It will seem to make a good difference in a set of worn points or mixture that is slightly off. I would recomend it though, it does allow the optimal air/fuel to be slightly leaner at idle and part throttle. If you intend to use an MSD and don't want to tune twice, then install it from the get-go. Make sure to get the MSD 6AL and run a Ford Duraspark distributor---the installation is simple and the Duraspark is a good distributor with relativly easy access to changing the settings.

Let me know if I can help,
 

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CougarAOD-
You are right, proper timing that increases power also increases fuel efficiency. The timing curve will be different whether you are driving on the street (widely varying conditions) or on the track (very predictable, repeatable conditions).

I mis-remembered my installation days. The "power vs. economy" charts were from the Holley 4v, and I think they had to do with fuel mixture? I'm not sure anymore, cause when I try to theorize how a richer or leaner mixture affects mileage and power, again they seem to go hand in hand... leaner mixture is more efficient, but is more prone to detonation (due to lower amounts of fuel to cool the mixture) and cylinder damage (due to the possible over-abundance of the oxidizer, oxygen, in the combustion process). I guess in racing applications, since the compression is typically much higher and the rpm range extends much farther, the added fuel is necessary to extend engine life and stave off detonation (which is also a function of timing)...

I think I've talked myself into a corner now.:)

I wish I had my Cougar up here to try these things on. Of course, maybe it's better that I don't have it..... ;)
 
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